Hot Topics Workshop:
Table of Contents
Background Information .......................................................................................................................................5
Investigating the Force of Wind .........................................................................................................................6
MODEL 1: States of Matter: Solids, Liquids, and Gas, Oh My! ............................................................6
MODEL 2: Density ................................................................................................................................................8
MODEL 3: Density of Fluids .............................................................................................................................9
MODEL 4: Kinetic Molecular Theory, or, Why is the Density of Warm Fluids different than
that of Cold Fluids? ........................................................................................................................................... 10
MODEL 5: Temperature versus Heat ........................................................................................................ 12
MODEL 6: Radiation, Conduction, Convection and Advection ....................................................... 13
MODEL 7: The Causes of Wind ................................................................................................................... 15
MODEL 8: The Case of the Hot Air Balloon ............................................................................................ 16
DEMO: Warm Fluid Rises? ............................................................................................................................ 17
Investigating Air in Motion ................................................................................................................................ 18
Protocol for See the Wind.............................................................................................................................. 18
Protocol for Hot Air Balloons ....................................................................................................................... 22
Protocol for Measuring the Wind ............................................................................................................... 27
Lift Force ................................................................................................................................................................... 27
MODEL 1: Newton’s Third Law ................................................................................................................... 28
MODEL 2: Lift Force: No fluid, no lift; No motion, no lift .................................................................. 29
MODEL 3: Putting it all together: How lift is created ......................................................................... 30
MODEL 4: Factors that affect lift................................................................................................................. 31
MODEL 5: The Lift Equation ......................................................................................................................... 32
Protocol: Modeling Lift Force with Human Air Molecules............................................................... 33
Location of Wind / Mapping Wind Data....................................................................................................... 36
MODEL 1: NREL Map of Infrastructure and Potential Renewable Energy Sources .............. 36
MODEL 2: Wind Power: Elevation versus Wind Speed ..................................................................... 37
MODEL 3: Wind Power Resources in the United States ................................................................... 38
MODEL 4: Zooming in on Missouri and the Saint Louis Metro Area ........................................... 40
Protocol: Graphing Wind and Solar Data ................................................................................................ 41
Protocol: Effect of Topography on Wind................................................................................................. 42
How do Turbines work? How Does a Generator Work?....................................................................... 51
MODEL 1: How energy is transformed in a fueled power plant. ................................................... 51
2 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 2: Inside a Wind Turbine............................................................................................................... 52
MODEL 3: Parts of a Wind Turbine ........................................................................................................... 53
Protocols: Build a Generator and Build a Small Wind Turbine...................................................... 54
Electricity Module ................................................................................................................................................. 57
MODEL 1: Electricity Symbols ..................................................................................................................... 57
MODEL 2: SERIES CIRCUIT versus PARALLEL CIRCUIT ................................................................. 58
MODEL 3: Batteries Connected in Parallel ............................................................................................. 59
Protocol: Investigating advantages of series and parallel battery connections ..................... 60
MODEL 4: Batteries Connected in Series ................................................................................................ 61
Protocol: Investigating electrical circuit factors that impact power of renewable energy
sources .................................................................................................................................................................. 62
Wind Turbines: How can we maximize their efficiency? ..................................................................... 69
MODEL 1: Wind Turbine Energy Conversion........................................................................................ 69
MODEL 2: Variables that Determine the Power in the Wind.......................................................... 70
MODEL 3: Scale Models .................................................................................................................................. 71
MODEL 4: How the Amp and the Volt work together in Electricity............................................. 72
MODEL 5: Power .............................................................................................................................................. 73
MODEL 6: Drag is a drag. .............................................................................................................................. 74
Protocol: Building the Most Efficient Turbine by Modifying Blade Design ............................. 75
Wind Turbine Blade Competition .............................................................................................................. 77
Culminating Project .............................................................................................................................................. 88
Wind Energy Expert Task: ............................................................................................................................ 89
Science Poster Rubric .......................................................................................................................................... 92
Wind Resources...................................................................................................................................................... 93
3 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Wind Energy :: Using Moving Air to Do
Work
OVERVIEW:
The Hot Topics Workshop
In this workshop, we focus on the composition and properties of fluids, like water and
air, and how these characteristics, combined with the energy of the sun, create wind.
We then investigate (1) the force of wind, (2) the presence of wind around the world,
and (3) the efficiency of wind turbines designed to convert the energy from wind to
electricity. The workshop culminates with a design competition to see what type of blade
design results in the most efficient turbine.
National Science Education Standards Addressed:
This interdisciplinary unit addresses the following standards as set forth by the Center
for Science, Mathematics, and Engineering Education:
Strand
Inquiry
5-8


Physical Science

9-12
Abilities necessary to
do scientific inquiry
Understanding of
scientific inquiry

Transfer of energy



Science and
Technology


Abilities of
technological design
Understanding about
science and
technology


Abilities necessary to do
scientific inquiry
Understanding of
scientific inquiry
Conservation of energy
and increase in disorder
Interactions of energy
and matter
Abilities of technological
design
Understanding about
science and technology
4 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Background Information
Wind Power
Wind power involves harnessing the wind’s energy, just as people have done for
hundreds of years to pump water or grind grain. Today’s equivalent, a wind turbine,
can use the wind’s energy to generate electricity. Wind turbines are mounted on a
tower, usually about 30 meters or more aboveground to take advantage of faster, less
turbulent wind and therefore capture the most energy. When the wind blows, a pocket
of low-pressure air forms on the downwind side of each blade. The low-pressure air
pocket then pulls the blade toward it (or, seen another way, the high pressure air on the
upwind side pushes the blade toward the downwind side), causing the rotor to turn.
This is called lift, similar to the force acting on an airplane wing. Indeed, the force of lift
is actually much stronger than the wind’s force against the front side of the blade, which
is called drag. The combination of the two causes the rotor to spin, and then the
turning shaft spins a generator to make electricity.
Stand-alone Wind Turbines
These are typically used for water pumping or communications. However, homeowners,
farmers and ranchers in windy areas can also use wind turbines to generate electricity
and decrease the cost of electricity.
Wind Systems
When wind turbines are connected to a utility power grid or combined with photovoltaic
systems, we consider them wind systems. These often require a large number of wind
turbines built close together to create a wind plant.
Types of Wind Turbines
Two types of wind machines, or turbines, are horizontal-axis and vertical-axis turbines,
based on the direction of the rotating shaft. Most wind machines today are horizontalaxis turbines, which look like windmills and have blades like airplane propellers.
Typically, these wind turbines stand as tall as a 20-story building and have three blades
that span 200 feet across. Vertical axis turbines look like eggbeaters and have blades
that go from top to bottom.
Considerations with Wind Energy
Wind is a clean fuel because the wind power plants produce no air or water pollution.
The most serious environmental drawbacks to wind machines may be the resources
needed to construct and maintain them, their negative effect on wild bird populations,
and the visual impact on the landscape.
5 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Investigating the Force of Wind
WHY?
Look up into the sky. What you cannot see is the air around you. However, this thin
layer of gases that surrounds the Earth has important characteristics and you need it to
survive. This atmosphere is a moving source of life for all living organisms on Earth. It is
mainly composed of nitrogen, but also contains gases such as oxygen, carbon dioxide,
argon and ozone. Importantly, the interaction among Earth’s air, water and land create
weather and climate. In order to understand how wind works, we must understand
properties of matter, including density, temperature, pressure, and buoyancy.
MODEL 1: States of Matter: Solids, Liquids, and Gas, Oh My!
1. Based on Model 1, what is the difference in the arrangement of atoms in solids,
liquids and gases?
2. The state of matter can change when certain physical causes are present. What
must happen for solid water to change to liquid water?
6 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
3. The state or phase of a material describes a physical state of matter. What is
significant about the word physical?
4. Besides change in phase, what are other examples of a physical change in
matter?
5. Based on model 1, what happens to the state of matter when energy is added?
What happens when it is taken away?
6. Fill out Table 1 below based on the model.
Table 1. Characteristics of the Phases of Matter
Solid
Liquid
Gas
Spacing
Potential for
Movement
Filling a
Container
7. Liquids and gases can be categorized as fluids. What is a fluid?
7 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 2: Density
1. What is the SI unit used to measure mass?
2. What is the SI unit used to measure volume? (hint – it’s not liters)
3. Using the Model and the answers to key questions 1 and 2, predict the SI unit
for density.
4. Calculate the density of a 1 m x 2 m x 0.5 m block of oak with a mass of 770 kg.
5. Calculate the density of a fluid that has a mass of 20 kg and a volume of 5 L.
6. Determine the mass of a copper bar with a density of 8.90 g/cm3 that occupies a
volume of 2.54 cm3.
8 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Warm
Water
MODEL 3: Density of Fluids
photo #1
photo #2
photo #3
Cold
Water
1. Did you read carefully? What color water is warm? What color water is cold?
2. What is the difference between photo #2 and photo #3?
3. Give an explanation for why the fluids do not mix in photo #3.
4. Predict what will happen if this setup is left for 1 hour.
5. Predict what will happen if the jars are reversed (the jar on the bottom is hot
and the one on top is cold). Explain your prediction.
9 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Extend:
6. Use your new understanding of how density affects floating/sinking:
MODEL 4: Kinetic Molecular Theory, or, Why is the Density of Warm Fluids
different than that of Cold Fluids?
The kinetic molecular theory is a model of how particles of matter behave. It is very
useful for explaining the forces between molecules and the energy that they possess, as
well as the effects of thermal energy, temperature and pressure on matter.
 All phases of matter (solid, liquid, and gas) are made up of tiny particles called
atoms. Often, the atoms that are joined to form molecules.
 These particles are in constant, random motion because they have a
temperature.
 Particles in motion possess kinetic energy. The average kinetic energy of the
particles is proportional to the material’s temperature in Kelvin.
 The particles’ motion increases as they gain energy (get hotter).
 There is a transfer of energy between particles (atoms and molecules) during a
collision between them.
10 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010

Particles (molecules or atoms) in gases do not exert large forces on each other,
unless they are in collision with each other.
1. What is kinetic energy?
2. What causes a gas to exert pressure on the walls when confined in a container?
3. As the temperature of a gas decreases, what change occurs in the average
amount of kinetic energy?
4. What property of gas particles is measured by temperature?
5. What is the relationship between temperature and molecular motion?
6. In terms of kinetic-molecular theory, how can an increase in the temperature of
a gas confined in a rigid container cause an increase in the pressure of the gas?
7. Based on this Model, explain why the density of a higher temperature gas is
LESS than that of a lower temperature gas if they have the same pressure.
11 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 5: Temperature versus Heat
Heat or thermal energy is the total
energy associated with the motion of
the gas molecules.
Because of the constant motion of all matter, all atoms have thermal (heat) energy.
Whenever a substance is heated, the atoms move faster and faster. When a substance
is cooled, the atoms move slower and slower. The "average motion" of the atoms that
we sense is what we call temperature. Temperature is a number. Kelvin is the SI unit
of measurement for temperature. Temperature is proportional to the average kinetic
energy of the molecules of a substance. Heat is an actual form of energy, measured in
Joules. It is a measure of the total energy associated with the motion of all the
molecules in a substance.
Using Model 5, complete the following statements with the word heat or temperature:
_________________ is a type of energy, but ________________ is not energy.
_________________ depends on the mass of the substance, while ______________
does not depend on the quantity of matter.
You can measure ____________________ directly with a device called a thermometer,
but ___________________ cannot be measured with a device directly.
If you give ________________ to matter, you either increase its ________________ or
change its phase.
12 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 6: Radiation, Conduction, Convection and Advection
1. List the three ways heat transfer can occur.
2. Advection is a term applied to horizontal transfer of heat by the wind. What form
of heat transfer is advection most similar to?
3. How does radiation transfer energy?
4. How does conduction transfer energy?
5. How does convection transfer energy?
13 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
6. Which modes of heat transfer require a medium? Which do not?
7. Explain how radiation, convection and conduction operate to create weather.
Use the diagram below to help you.
14 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 7: The Causes of Wind
When the sunrays hit the surface of the earth it is heated. There is a difference
between how fast the land and sea are heated. The land is heated much faster than the
sea. The air above land is heated faster than the air above the sea. The hot air above
land rises high into the sky, where it cools off. High in the sky the cold air now moves
out over the sea. Here it sinks down, pressing cool air towards land. The air moving
towards land is what we know as wind. This means that it is the sun that makes the
wind blow. At night the process reverses because the sea is warmer than the land.
15 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
1. Based on the Model, what type of air “rises”?
2. Based on the Model, what type of air is less dense?
3. Based on the Model, explain why the following statement is true: The energy in
wind comes from the sun.
4. Based on the Model, explain the “sea breeze” and how it differs during the day
and at night.
MODEL 8: The Case of the Hot Air Balloon
Hot air balloons use the principles
explored above to make them soar over
Forest Park
16 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Fill out the following passage with the terms HOT or COLD
___________ air is less dense than ___________ air. __________ air molecules have
been accelerated by heat causing fewer molecules to occupy the same space. A much
greater number of molecules occupy the same space in ___________ air. With fewer
molecules, ________ air has less mass, and is therefore more buoyant than an equal
volume of _________ air.
1. In the figure in Model 8, the particles inside the balloon move faster than those
outside the balloon. How might you get this to happen?
2. A cubic foot of air has a mass of 28 grams. What is its density?
3. When the air is heated, a cubic foot of it now has a mass of 7 grams. What is its
density after heating?
4. Explain what will happen if the air in question 1 comes into contact with the air
in question 2.
5. Using this Model, explain how a hot air balloon takes into account movement of
molecules in order to fly.
DEMO: Warm Fluid Rises?
Convection is the movement of heat in a fluid, which can be a liquid or a gas.
Convection is at work when warm air and cold air meet. In order to see how fluids
move due to differences in temperature, do this demonstration of Model 3.
17 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Materials:
2 clear 2-Liter bottles
Warm water
Food coloring
Cold water
Index card or plastic playing card (preferred)
Figure 1.
Figure 2.
1. Take a bottle, fill it with cold water
2. Take a bottle, fill it with warm water and add food coloring
3. Place an card on top of the bottle of cold water and put the card and bottle
upside down on top of the warm water bottle (Figure 1)
4. Carefully remove the index card so the spouts are aligned (Figure 2)
5. Make observations
Investigating Air in Motion
Purpose:
The goal of these laboratory investigations is to help students to see the wind using a
homemade kite, determine the difference in the speed and smoothness of the wind at
different altitudes above the Earth, and identify variables that will impact the hot air
balloon they will create and launch.
Protocol for See the Wind
Background:
18 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
A kite is a tethered aircraft that flies due to the lift created when the air flows over and
under the kite’s wing, producing low pressure above the wing and high pressure below
it. Kites are usually heavier than air, so they will fall when the wind stops. Kites were
used recreationally more than 2,800 years ago in China, but by the 18th and 19th
centuries kites were being used as vehicles for scientific research. Kites were the
precursors to the traditional aircraft and were instrumental in the development of early
flying machines. Today, we will experiment with kites to see how the air is able to lift
the kite in the air and how kites show us, qualitatively, the speed and direction of wind.
Materials:
Tissue paper or plastic from a bag, 17 x 22 cm
Two drinking straws, cut to a length of 17 cm
Strong thread – e.g. made of polyester
Scotch tape
Paper hole puncher
Scissors
Metric ruler
Procedure
1. Cut out the kite using the pattern on the next page. You can make several kites
at a time by cutting through several layers of paper.
2. Put tape – about 4-6 layers – over the two corners in the sides and punch out
the two holes with the hole punch.
3. Tape the two straws to the kite.
4. Tie a piece of kite string that is 66 – 90 cm long between the two holes in the
big kite.
5. Find the middle of the string and make a loop (with a knot) exactly halfway
between the two holes. Tie the kite string to the loop.
6. Wind conditions vary a lot. Bring the kite around to different parts of the school
and find places where the wind is very turbulent and places where the wind is
steady.
19 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
20 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
21 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Protocol for Hot Air Balloons
Background:
Hot air is less dense than cold air. Heat accelerates the motion of the air molecules
causing fewer molecules to occupy the same space as a much greater number of
molecules do at a lower temperature. With fewer molecules, the hot air has less mass
and is therefore more buoyant than an equal volume of colder air. Hot air balloons use
these principles to create a human-carrying balloon aircraft that can be propelled
through the air or pushed along by the wind.
When the hot air escapes,
cold dense air comes in
the bottom to replace it.
Thus, the balloon gains
mass and becomes less
buoyant.
See video: http://videos.howstuffworks.com/howstuffworks/43-how-hot-air-balloons-work-video.htm
Materials:
Version 1:
22 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Dry cleaning bags
Several small paper clips
Scotch tape
Heat source (blow dryer or heat gun)
Version 2 (Materials for ONE hot air balloon)
12 cardboard panel templates for the tissue paper
18 sheets of tissue paper per group (i.e., per balloon)
24 glue sticks (shared among the class)
24 scissors (shared among the class)
24 markers (any color is fine; preferably not thin-tipped, so as not to tear the tissue
paper)
heat gun (shared by the class)
2 pennies per group (i.e., 2 per balloon)
1 4-inch (or so) piece of twine per group (i.e., per balloon)
Procedure:
Version 1:
1. Seal any opening and tears in the upper end of the bag with a minimum amount
of tape. Tape is heavy.
2. Attach several paper clips to the plastic around the lower opening. This number
may need to be changed, but can be optimized during experimentation.
3. Turn on the blow dryer or heat gun.
4. Spread the bag opening wide to capture the hot air while supporting the upper
end with your hand. Be sure to keep the bag open!
5. When the bag is inflated with hot air, test its buoyancy by letting it go for a
moment. If it rises quickly, stand back and let it fly.
6. If not, make adjustments (paper clips, strength/temperature of heat source, etc.)
Version 2:
1. Glue the edges of 3 sheets of tissue paper together, overlapping by 1-2 cm. See
Fig. 1. Repeat this 6 times so that there are 6 “panels”.
23 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
2. Fold each panel in half lengthwise. See Fig. 2.
3. For each panel: lay a template on top so that the long, straight edge of the
template lies against the folded edge of the panel. Make sure that the “longer,”
thinner edge of the template lies along the longer, thinner edge of the panel
(otherwise, you will find that there won’t be enough room). Trace the template
with the marker, and cut out the shape. Do this with each panel. See Fig. 3.
4. Stack the 6 folded panels on top of each other, such that the folded edges,
“tops”, and “bottoms” align with each other.
5. Using a glue stick, glue the unfolded edges of all 6 panels together so that the
whole thing, once glued together, looks like one long accordion. Be careful not
to glue a panel to itself! Also, be careful that nothing tears and that there are no
holes along the glued border. See Fig. 4.
24 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
6. Bring the two remaining unglued edges around so that they meet, and so that
the glued “seams” are inside the balloon shape. Glue these edges together. See
Fig. 5. You should now have a round, balloon-like 3D shape.
7. Bunch the top of the balloon together and tie together with the twine. See Fig. 6.
25 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
8. Glue the two pennies to the open, bottom end of the balloon, and one on either
side of the inside of the opening. These pennies will help stabilize the bottom so
that the balloon doesn’t flip over once inflated. See Fig. 7.
9. Check the balloon for any openings or tears. Gluing small patches of tissue
paper over any openings can easily repair these.
10. LAUNCHING: While one person holds the balloon from the top, have two other
people hold the bottom of the balloon open over the heat gun. After a few
minutes, the balloon should be inflated enough that no one need hold it from the
top, and after a few more minutes, the balloon can be released completely, and
should hopefully float to the top of the ceiling!
11. As the balloon is being inflated, any holes or tears should be more easily
identified, and can be repaired while still inflated.
12. Launching works best in a cold room. We’ve done this in both a warm and a
cold room, and the balloons floated much, much higher in the cold room.
26 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Protocol for Measuring the Wind
Purpose: To measure the quality and intensity of wind under various conditions
Materials:
Large sturdy kites OR large helium filled balloons
Kite string
Streamers
Wind speed meter
Windy day!
Procedure:
1. Tie 15 – 30 m of kite string to the kite/balloon
2. Cut 1.5 meter sections of streamers to attach to the string.
NOTE: This is adding extra weight to the kite or balloon so
the kite and balloon must be large – you can also use
multiple balloons.
3. Tie 5-10 streamers to the string at 3 meter intervals. If you have a lot of string
you can attach more to gather more data!
4. Use a wind meter (anemometer) to get a base reading of wind velocity at the
ground.
5. Take a reading higher up from the roof of the building or by attaching the wind
meter to your kite/balloon.
6. Take the kite/balloon outside.
7. Release it into the air.
8. Draw a picture and record observations.
Lift Force
WHY?
Lift is a mechanical force generated by a solid object moving through a fluid or a fluid moving
past a solid object. Lift force maintains airplanes and even birds in the air. Lift force makes
wind turbines rotate, as the flow passes by the blades. Lift occurs when a moving flow of gas is
turned (deflected) by a solid object. The flow is turned in one direction, and the lift is
generated in the opposite direction (for every action there is an equal and opposite reaction =
27 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Newton’s Third Law). Because air is a fluid made up of gas molecules that are free to move
about, any solid surface can deflect a flow.
MODEL 1: Newton’s Third Law
A force is a push or a pull upon an object. This implies there must be two objects: one being
pushed and on doing the pushing. Thus, forces result from interactions between objects.
According to Newton’s Third Law, whenever objects interact with each other they exert forces
upon each other. These two forces the objects exert on each other are called a Newton’s Third
Law force pair. Friction, like all other forces, obeys Newton’s Third Law. For example, if you
want to swim, you push the water behind yourself. When you push the water back, the water
pushes you forward.
1. All forces result because of ___________________________ between objects.
2. Forces come in pairs. What are these pairs called?
3. The force pairs are drawn on the diagram of the rocket ship.
Which direction is the force on the rocket? Which direction is
the force on the propellant?
4. How is motion possible if all forces in the universe come in pairs
that are equal and opposite?
28 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 2: Lift Force: No fluid, no lift; No motion, no lift
For lift to be generated, the solid body must be in contact with the fluid. For lift to be
generated, there must be a difference in velocity between the solid object and the fluid.
1. Based on the model, what fluid is the wind turbine in contact with?
2. Based on the model, is the solid object moving through a static fluid or is the fluid
moving past a static solid object?
3. If lift acts perpendicular to the fluid flow, and drag acts in the direction the fluid is
going, draw an arrow for LIFT and DRAG on the sketch of the wing where wind flow and
rotation are labeled.
4. Name the two forces that make a Newton’s Third Law force pair in the case of the wind
turbine.
29 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 3: Putting it all together: How lift is created
Air approaching the top surface of the wing is sped up and compressed into the air above as it
moves upward. As the top surface of the wing curves downward and away from the airstream,
a low-pressure area is developed, and air is pulled downward toward the back of the wing.
As air approaches the bottom surface of the wing, it is slowed, compressed and redirected in a
downward path. The overall pressure effects on the bottom of the wing are generally less
pronounced than on the top of the wing. When you sum up all the pressures acting on the
wing, there is a net force upward on the wing. As the amount of airflow turned downward by a
given wing is increased, the speed and pressure differences between the top and bottom
surfaces become more pronounced, increasing the lift.
A. Air approaching top surface of wing
B. Air approaching bottom surface of wing
C. Lift force
D. _________________
E. Drag force
1. What are letters A and B in the figure referring to?
2. What are C and E referring to?
3. Based on the model, what is letter D in the figure referring to? (hint – it’s related to C
and E.)
30 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
4. Which surface of the wing has faster moving air particles?
5. Which surface of the wing has higher pressure, top or bottom?
6. How does this model take into account Newton’s Third Law?
MODEL 4: Factors that affect lift
To create lift you need a flow of air. Lift can occur on an aerodynamic curved airfoil (wing or
propeller blade) or on a simple flat plate, if it is inclined to the flow.
1. The figure in the top left shows a curved airfoil. What do the yellow lines represent?
31 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
2. What do the yellow lines tell you about the speed and pressure of the air at each
surface of the airfoil?
3. What are the three overarching categories that can vary to affect lift?
4. Predict the optimal conditions for the object.
5. Predict the optimal conditions for motion.
6. Predict the optimal conditions of the air.
MODEL 5: The Lift Equation
We can gather all of this information on the factors that affect lift into a single mathematical
equation called the Lift Equation. The lift equation predicts how much lift force a given body
moving at a given speed will generate:
The coefficient of lift, , contains all the complex features of the wing design, and it usually is
determined experimentally.
Calculate lift of an airplane with a wingspan of 40 feet and a chord length of 4 feet (total wing
area = 160 sq. ft.), moving at a speed of 100 mph at sea level. Let’s assume that the wing has
a constant cross-section using an NACA 1408 airfoil shape and that the plane is flying so that
the angle of attack of the wing is 4 degrees.
32 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Wing area =____________ square feet
Air density = 0.0023769 slugs/cubic foot (at sea level on a standard day)
Velocity = _______________ feet per second
Lift Coefficient = 0.55 (lift coefficient for NACA 1408 airfoil at 4 degrees angle of attack)
No unit conversions are necessary if you use only the British Imperial System. Your
lift will be in pounds. Calculate lift in the space below. SHOW YOUR WORK!
If the plane goes twice as fast, how does the lift change?
Protocol: Modeling Lift Force with Human Air Molecules
33 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Background:
One of the most common ways to explain lift involves the idea of equal time. Unfortunately, it
has a serious flaw – it’s not true! However, the equal time model can be helpful to our
understanding because it is a step towards the truth. The truth is very complicated.
In the equal time model, a pocket of air above the wing
takes the same time to reach the back of the wing as a
pocket of air under the wing. In fact, the pocket of air
that is forced to go over the wing actually reaches the
back of the wing before the air that goes under the
wing. So, the air above the wing is not only going a
longer distance, but it is also taking less time. This
means that the air above the wing is going MUCH faster
than the air below the wing. The exercise we will try
today provides a lower bound on the difference between
the speed of air above and below the wing.
Materials:
Figure 1 - Air going above the wing takes LESS time to
reach the back of the wing
20 cones
Meter Stick
Stopwatch
Calculator
Procedure:
Figure 2 - Set up cones like this
1. Move outdoors or to the gym
2. Arrange the 20 cones as shown in the figure to form the cross section of an aircraft wing
(an airfoil)
3. Using the meterstick, measure and record the perimeter of the lower and upper sides of
the airfoil
4. Organize into two lines of equal numbers of students. The lines must be shoulder-toshoulder until they reach the airfoil.
5. Determine a signal for each line to start running to the end of the airfoil
6. Signal the line and start the stopwatch
7. Time how long it takes each pair of students (from line 1 and 2) to get to the end of the
airfoil (NOTE: students must arrive at the back of the airfoil at the SAME TIME)
8. To find the effective velocity of your wing, divide the lower perimeter by time
9. Using the lift equation and the calculator, calculate the lift generated by each student
(NOTE: Set the coefficient, density, and area equal to 1)
34 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Questions:
1. Why did the students that ran around the upper side of the airfoil exert more physical
effort?
2. What determined the highest and lowest values of lift force?
3. What can be done to increase the lift force?
4. Why are wind turbine blades so long (i.e., 50 meters each)?
5. The lift force on the blades causes the turbine to rotate. Any force that acts to cause a
rotation is called a torque. What would be needed to make wind turbines rotate faster
while generating a greater torque?
6. How might the speed of the wind be increased?
35 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Location of Wind / Mapping Wind Data
WHY?
Certain areas in the United States and locations globally are more suited for particular forms of
renewable energy usage. For example, you would not choose to install a solar panel unless
your region received significant amount of direct sunlight each year. In addition, certain
locationrs around the United States receive more wind than others. Wind speed varies based
on location and elevation. Today, the Great Plains and the Midwest regions have much of the
potential for wind power due to a favorable combination of characteristics: ample wind
resources, an extensive rail and highway network for shipping turbine components, flat
topography, and broader acceptance from farmers and ranchers. It is very important to use
what you know about your region to predict which energy source will provide the most power.
MODEL 1: NREL Map of Infrastructure and Potential Renewable Energy Sources
1. Find Missouri. Which three renewable energy sources have the most potential?
2. Identify the top 3 locations where wind energy has the most potential in the United
States.
3. What do you notice about the locations with the most potential for wind energy?
36 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 2: Wind Power: Elevation versus Wind Speed
1. Based on Model 2, what is the difference between a wind class of 1, 3 and 5?
2. Based on Model 2, what wind class has the greatest potential for wind power?
3. What happens to the speed of wind at greater elevations?
37 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
4. Based on the graph above, why is it important to understand wind speed?
MODEL 3: Wind Power Resources in the United States
http://geosci.uchicago.edu/~moyer/GEOS24705/Images/us_windmap_80meters.png
1. Based on Model 3, what region(s) of the United States have the most potential
for land-based wind power?
2. What state(s) in the United States have regions of outstanding or superb resource
potential?
3. Using the topographical map below and your knowledge of science, why do these
regions have the most capacity for wind power?
38 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Figure 3 - Topographical Map of the USA
4. Compare the map below that shows installed wind power capacity per state with the
map of wind resources on the previous page. What glaring issues can you find?
39 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 4: Zooming in on Missouri and the Saint Louis Metro Area
1. What regions of Missouri are most suitable for wind energy development?
2. What regions of Missouri are least suitable for wind energy development?
3. Why shouldn’t we install turbines where there isn’t much wind? List at least three
reasons.
40 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Protocol: Graphing Wind and Solar Data
Purpose:
To locate data in almanacs or other resources regarding average wind velocity and number
of sunny days for various cities in the United States. Accurately display this on a map of
the United States. Then, determine which regions of the continental United States seem to
be best suited for wind/solar energy development.
Background:
Solar energy is the original source of almost all forms of energy on Earth. The extent to
which a residence benefits from the sun's energy depends on the structure's efficiency,
orientation and landscaping. Wind energy is derived from solar energy. The uneven
heating of the earth's surface by the sun gives rise to large-scale circulation within the
atmosphere (jet stream, etc.) and also to small scale or local winds. Obviously areas of the
continental United States that receive the most sunlight and areas having sufficient average
wind speeds are the prime areas for development of solar and wind energy use. In this
activity you will plot wind speed data and also solar data to identify areas of the U.S. that
seem to be good areas for wind and solar energy use. There are typical wind speeds or
classes of wind throughout the U.S. Classes range from 1 (the lowest) to 7 (the highest).
Materials:
3D map of Missouri
Almanacs or other resources showing wind and solar data in the U.S.
Copies of continental United States map outline
Atlas, or U.S. road map
Procedure:
1. Use current almanacs to find data on average wind speeds and also the number of sunny
days for U.S. cities.
2. Then locate each city for which data is given on the blank U.S. outline map and display
the data.
3. Use one color for wind velocity and another color for number of sunny days.
4. Draw lines around areas of the U.S. that appear to have the highest number of sunny
days and the highest wind speeds.
5. Compare your map to the NREL map of wind resource potential.
6. Summarize in paragraph form what you found out about the sunniest and windiest areas
and how it compares to current research and wind power utilization.
Extension Activity:
Obtain data on average wind speed for various cities in Missouri. Contact your nearest
National Weather Service office to obtain the data.
41 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Protocol: Effect of Topography on Wind
Purpose: To understand how topography and elevation affect wind speed and to identify
optimal locations for wind farms based on wind speed.
Testable Question: How do elevation and geographical features affect wind speed?
Materials:
High-speed fans or box fans
Objects of different size that will not blow away (ex: blankets, books, weighted boxes)
20 wind flags (string or tissue, popsicle stick or toothpick, and clay to hold it up)
Missouri topographical map
Missouri wind speed map at 80m
Missouri wind farm map (below)
Procedure:
PRELAB
1. Collect the materials for creating the topography – books, backpacks, blankets, or
weighted boxes can be used to create mountains and valleys.
2. Make 20 “wind flags”
3. Make color copies of wind maps
PRELAB QUESTIONS:
1.
2.
3.
4.
Where have you noticed lots of wind?
Where would you go to fly a kite?
What geographical features influence the speed of wind?
Do we have wind farms in our state?
42 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
5. Is it windier in a forest or in a field? On a hill or in a valley?
6. What is your hypothesis about the effect of elevation on wind speed?
7. What is the independent variable in this investigation?
8. What is the dependent variable?
9. What variables do you need to control?
10. What parts of the United States do you think have the best wind for energy production?
LAB
1. Using the objects around the classroom, create a model landscape. This landscape
must include: a mountain range, rolling hills, valleys, plateaus, and open areas. It may
include buildings.
2. Number the wind flags 1 through 20.
3. Create a wind farm by placing the 20 flags where you think they will get the most wind.
4. Place the box fan next to the landscape and turn it on.
5. Record which flags are blowing and at what height.
6. For trial 2, move the box fan to another location for new wind direction.
7. Record which flags are blowing and at what height.
8. Based on what you learned, place the wind flags onto the 3D map of Missouri indicating
where you feel there will be the most wind in the state.
9. Compare your prediction to the actual wind speed map.
Data Table:
43 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Observations:
44 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Were there some flags that never received any wind? Where were they located?
Were there some flags that always received wind? Where were they located?
45 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Conclusion:
Write a conclusion for this investigation. In your conclusion, be sure to:



Answer the testable question
Include supporting data from the data table
Explain how these data support your conclusion
46 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
POSTLAB QUESTIONS:
1. Where are the windiest areas?
2. Are there any trends? If so, what do you notice?
3. How do wind speeds change as the elevation increases?
4. Why do you think this is the case?
5. Do you think this effect goes on forever as elevation increases?
6. Where do you think the most desirable areas for wind farms are?
7. Why do you think these locations were selected?
8. What role do you think elevation plays in the height of turbines?
9. Where are the wind farms in Missouri?
10. Are turbines always in the windiest spots? Why or why not?
47 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
48 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
49 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Wind Capital Group’s Current Projects
Based on this map and the knowledge gained from this investigation, does the location of
this company’s operating wind projects make sense? Why or why not?
50 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
How do Turbines work? How Does a Generator Work?
WHY?
Electricity is generated in a power plant. Thermal power plants have big boilers that burn
fuel to make heat. This heat is used to boil water and create steam. The steam comes
through a tiny hole on the top of the spout that is piped through a turbine. The moving
turbine moves the generator, which has a long, coiled wire on its shaft surrounded by a
giant magnet. The shaft inside the generator turns as the turbine turns, converting
mechanical energy into electrical energy based on the fascinating principle of
electromagnetic induction. A wind turbine works in a similar way, except that the wind
turbine itself creates the motion to turn the shaft of the generator and make electricity.
MODEL 1: How energy is transformed in a fueled power plant.
During this entire process, energy is transferred from one form to another several times.
Describe four energy changes that occur during the process.
51 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 2: Inside a Wind Turbine
1.
Where are the blades located?
2.
To what are the blades attached?
3.
Based on Models 1 and 2, what is the
purpose of the generator?
4. What do you think the optimum height of the tower is?
5. The gear transmission box causes turning speed to increase. How might this
enhance efficiency?
6. What must be inside the tower for the turbine to be effective?
52 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 3: Parts of a Wind Turbine
Nacelle – The nacelle sits atop the tower and contains the gearbox, low- and high-speed shafts,
generator, controller, and brake. Some nacelles are large enough for a helicopter to land on them!
Blades – Most turbines have either two or three blades. Wind blowing over the blades gives the blades
lift and thereby rotates the turbine.
Tower – Towers are made from tubular steel, concrete, or steel lattice. Because wind speed increases
with height, taller towers enable turbines to capture more energy and generate more electricity.
Foundation (base) – The base provides counterweight and stability for the tower. Made with concrete
and rebar, the base anchors the tower to the ground.
Create vocabulary study cards with the parts of wind turbines. Be sure to include a picture.
53 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Protocols: Build a Generator and Build a Small Wind Turbine
Purpose: To investigate the structure and function of generators and turbines used to
maximize wind power
Background:
You are already familiar with a small
electrical motor. When you switch the motor on it
starts running. This happens with many different
home appliances such as a blender, an electrical
train, or a fan. However, most motors can also be
used as generators.
A generator acts upon the link between the
phenomena of electricity and magnetism. A
generator is simply a device that moves a magnet
near a wire to create a steady flow of electrons
(called a current). The action that forces this movement varies greatly, ranging from hand
cranks and steam engines to nuclear fission, but the principle remains exactly the same.
One simple way to think about a generator is to imagine it acting like a pump
pushing water through a pipe. Instead of pushing water, a generator uses a magnet to
push electrons along. This is a slight oversimplification, but it paints a helpful picture of the
properties at work in a generator. A water pump moves a certain number of water
molecules and applies a certain amount of pressure to them. In the same way, the magnet
in a generator pushes a certain number of electrons along and applies a certain amount of
electric "pressure" to the electrons.
In an electrical circuit, the number of electrons in motion is called the amperage or
current, and is measured in amps. The "pressure" pushing the electrons along is called the
voltage and is measured in volts. For instance, a small generator spinning at 1,000
rotations per minute might produce 1 amp at 6 volts. The 1 amp is the rate of electrons
moving (1 amp physically means that 6.24 x 1018 electrons move past a spot in the wire
every second), and the voltage is the amount of pressure behind those electrons.
Build a Generator
Materials:
Motor with pulley
Cables
3 Volt light bulb
Socket
Testable Question: Can you use a motor and a multimeter to generate electricity? If so,
how much electricity can you generate?
54 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Procedure:
1. Fasten the motor to the cables
2. Put the pulley on the shaft.
3. Connect the cables to a light bulb and see what happens when you turn the shaft.
Build a Mechanical Windmill
Materials:
A thick drinking straw, 18 cm
long
A flower stick, approx. 3-5 mm
wide, 25 cm long
Sewing thread
Paper
1 cork
2 scraps of aquarium tubing
2 washers, of a size fitting the
flower stick
A push pin
Paper clips
Glue
Tubing
Procedure:
1. Fix the cork to the flower stick, which will be the shaft of the wind turbine model.
2. Then put on scrap of tubing, a washer, the straw, the second washer and the
second scrap of tubing (in that order).
3. Attach the sewing thread to the flower stick with glue or a rubber band.
4. Make a rotor from a piece of paper by following the instructions shown in the figure.
5. Fix the rotor to the cork using a pin and some glue.
6. Bend the nail to form a hook and tie it to the end of the string.
7. Try to lift things with the hook by giving your turbine a source of wind.
Hint – you may be able to lift much more than you expect, just by walking around with
your windmill.
55 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Tubing
56 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Electricity Module
WHY?
Electricity is a secondary energy source or an energy carrier. This means that we must get
electricity from the conversion of other sources of energy, such as wind and solar energy. Wind
and solar are examples of primary energy sources. The primary energy sources we use can be
renewable or non-renewable, but electricity itself is neither renewable nor non-renewable. We
use electricity every day to do a variety of jobs for us – from lighting, heating, and cooling our
homes to powering our televisions and computers! However, despite the importance of
electricity to our lives, we rarely stop to think about how electricity really works. To gain a true
understanding of wind energy, we must not only understand how mechanical energy is
transformed into electricity, but it is also essential to understand the fundamentals of electricity.
MODEL 1: Electricity Symbols
Based on your knowledge of electricity, use the following words to correctly identify the pictures
and symbols that represent parts of electricity: voltage source, conductor, load, switch.
Place each word in the appropriate box above.
57 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Here is a sample circuit
diagram. What do you think
this circuit does?
MODEL 2: SERIES CIRCUIT versus PARALLEL CIRCUIT
1. Based on the model, differentiate between a series circuit and a parallel circuit in terms
of number of paths for electrons to follow.
58 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 3: Batteries Connected in Parallel
KEY:
V = volt
Ah = ampere*hours: how many amp*hours can be pulled from the battery at a certain voltage
Example: If you have a fully charged 12 V, 100 Ah battery, you may pull 1 Amp of current at
12 V for 100 hours.
In the picture above, you have the equivalent of a fully charged 400 Ah battery. Follow the
example above to explain what this means.
59 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
Protocol: Investigating advantages of series and parallel battery connections
Background:
A series circuit has just one path for the electrons to take – all the circuit elements are in line
(series) with each other. A parallel circuit has multiple (parallel) paths electrons can take, but
the paths eventually lead to the same place. In this lab, we investigate the distinctions
between series and parallel power supplies. We start with batteries and move to capacitors. A
capacitor is a device that stores energy by separating positive and negative charges. The
capacitors are different because they drain quickly when they power the loads we have chosen.
This enables us to study how quickly the circuit uses energy from the power supply.
Materials:
Wires with alligator clips (conductors)
light bulb base
small motor (load)
three D cell batteries (per group)
small (1 W) light bulb (load)
three 1 F capacitors (per group)
clock or timers
Testable Question ______________________________________________
Procedure:
1. Examine the speed of the motor or the brightness of the bulb with one, two, or three
batteries connected in series or parallel.
2. It is tricky to understand the advantage of the parallel configuration. To do so, we will
charge capacitors and let THEM power the load. Using wires, connect the positive
terminal of the battery to the positive terminal of the capacitor and the negative
terminal of the battery to the negative terminal of the capacitor.
3. Leave these connections for 30 seconds, and then charge the other capacitors in the
same way.
4. Once the three capacitors are charged, try connecting them in different ways to the
bulb. Once a capacitor has discharged, you can recharge it using steps 2 and 3 as often
as you like. Can you find the advantage of connecting the capacitors in parallel? The
same advantage is present for batteries, but it is harder to observe!
60 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
MODEL 4: Batteries Connected in Series
1. In Model 4, the batteries are connected to make the equivalent of a fully charged 48 V,
100 Ah battery. Use the example in Model 3 to explain what this means.
Use Models 3 and 4 to answer the following questions:
2. Which set up produces the most voltage?
3. Which set up produces the most current through the load (i.e., brightest light, fastest
motor)?
4. Which setup could power the load for the longest time?
61 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
5. Explain how voltage, current, and the time current can flow change when batteries (or
capacitors) are connected in parallel and in series.
Protocol: Investigating electrical circuit factors that impact power of renewable energy
sources
Background:
Photovoltaic cells, like those used in solar powered calculators, convert sunlight directly into
electricity. Photovoltaic (PV) cells are made of silicon, which is a special type of material called
a semiconductor. When light strikes the cell, a certain portion of the light is absorbed within
the semiconductor material. The light energy knocks electrons loose, allowing them to flow
freely. By placing metal contacts on the top and bottom of the PV cell, we can draw the current
off for external use. This current, multiplied by the cell’s voltage defines the power that the
solar cell can produce. In this lab you will investigate the factors that impact the amount of
power a silicon solar cell can produce. This lab focuses on the impact of connecting silicon solar
cells in parallel and in series.
Materials:
2.0 V silicon solar cells
light bulb base
wires with alligator clips (conductors)
60 W light bulb
small motor (load)
lamp
small (1 W) light bulb (load)
TESTABLE QUESTION: ___________________________________________
Procedure:
1.
2.
3.
4.
5.
Take out one solar cell.
Using the solar cell with alligator clips connect the cell to the voltmeter
Record the voltage produced by the solar cell.
Turn on the 60 W light bulb and face the solar cell towards it.
Record the voltage produced by the solar cell.
62 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation ::
Washington University in St. Louis, January 15, 2010
6. Take the solar cell outside or point the solar cell towards the window. Record the
voltage produced.
Position and Light Conditions
Voltage Produced
(____________________________variable)
(_________________________________ variable)
Flat on table, lights in the room only
Facing the 60 W bulb
Facing the window or outside in sunlight
7. Make a complete circuit using the wires, one solar cell and the motor.
8. Draw a picture of this circuit and label all parts. Record observations.
OBSERVATION: Explain the movement of the motor. How does it change if you move the
solar cell or add additional light?
__________________________________________________________________
__________________________________________________________________
9. Switch the wires that are connected to the motor so that it is now opposite.
63 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
OBSERVATION: What happens to the movement of the motor?
__________________________________________________________________
__________________________________________________________________
10. Change the load to a small light bulb. Draw a picture of this circuit and label all parts.
Record observations.
OBSERVATION: Explain how bright the light is. How does it change if you move the solar
cell or provide it more light?
__________________________________________________________________
__________________________________________________________________
11. Take out another solar cell. Connect the solar cells in series with the motor attached as
the load. Record observations.
OBSERVATION: Does the motor spin faster or slower with two solar cells in series? Explain
why this is happening.
__________________________________________________________________
__________________________________________________________________
12. Cover up one of the solar cells with your hand so that it does not obtain any light.
Record observations.
OBSERVATION:______________________________________________________
13. Disconnect the motor and connect the solar cells to the voltmeter in series. Place the
solar cells connected in series in the sun and then in the “shade.” Record observations.
64 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
OBSERVATIONS:_____________________________________________________
_________________________________________________________________
14. Connect the two solar cells in parallel to the motor. Make observations.
OBSERVATIONS:_____________________________________________________
_________________________________________________________________
15. Does the motor spin faster or slower with two solar cells? Explain why this is
happening.
OBSERVATIONS:_____________________________________________________
__________________________________________________________________
16. Cover up one of the solar cells with your hand so that it does not obtain light. Record
observations.
OBSERVATION:
________________________________________________________________
17. Connect the solar cells in parallel to a voltmeter. Place the solar cells connected in
series in the sun and then in the shade. Record observations.
OBSERVATIONS:_____________________________________________________
________________________________________________________________
QUESTIONS:
1. What type of light produced the highest voltage? What was this voltage?
_______________________________________________________________________
_______________________________________________________________________
_____________________________________________________
2. When you connected 2 solar panels in series, how did that affect the load?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________
65 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
3. Draw a picture of the 2 solar panels in series in the space below:
4. How do you know that it is in series?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
5. Look at the diagram below. What kind of circuit is this: Closed or open? Series or
parallel? Explain.
_______________________________________________________________________
_______________________________________________________________________
66 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
_______________________________________________________________________
_______________________________________________________________________
6. What differences did you observe between the 2 solar cells connected in series and
connected in parallel in terms of voltage, current, and performance of the load?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
7. Explain this difference based on your knowledge of electrical circuits.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
8. Based on this experiment, if you were placing photovoltaic cells on the roof of the
school, would you prefer that they be connected in series or in parallel? Explain.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
9. Solar cells can also be called photovoltaic cells. Remember: photo=light and
voltaic=electricity. Why is this a good name for this technology?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
10. What other words can you think of that contain the prefix “photo”?
_________________________________________________________________________________________________________
_______________________________________________________________________________
CONCLUSION:
In your own words, write a conclusion to this lab. Be sure to:



Answer the investigative or testable question
Include supporting data
Explain how the data support your conclusion
67 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
68 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Wind Turbines: How can we maximize their efficiency?
WHY?
Wind turbines convert kinetic energy in the wind into mechanical energy of a rotating shaft.
This rotating mechanical energy is converted by a generator into electrical energy. The
efficiency of the turbine depends on the amount of energy in the wind, the amount of energy
that the wind turbine can “catch,” and the amount of the wind’s energy that can be converted
into useful electrical energy. Certain variables determine the power of the wind and the blade
design is a crucial factor in capturing as much wind energy as possible.
MODEL 1: Wind Turbine Energy Conversion
D = diameter of turbine blades
Blue oval = circular area of wind swept by the blades
What energy transformation occurs in the wind turbine?
Why is the wind slower after it passes the turbine?
69 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
MODEL 2: Variables that Determine the Power in the Wind
1. What three variables affect the power in the wind?
2. Which of these variables has the greatest impact on wind power? Explain.
3. Power is measured in Watts. How much power is in the wind from a regular circular
house fan?
Information:
V – 5 m/s
 – 1.0 kg/m3
D – 0.4 m
A – 0.125 m2
70 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
MODEL 3: Scale Models
The Windy City Corporation has decided to build a 20 turbine wind farm 6 km (3.3 mi) off the
coast of the United States. As this will be the first project of this kind, we need to construct a
scale model to see what it will look like in miniature.
1. Convert the units for the real tower and model to be the same. (Convert 55 m to
cm).
2. Construct a model tower. Make its height 5.5 cm.
3. Find the Model Scale by finding and reducing the ratio of the Model Height : Tower
Height.
4. Using the same scale, what should the diameter of the model’s blades be?
71 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
MODEL 4: How the Amp and the Volt work together in Electricity
Electricity flows in a wire in the same way as the water flows in the hose. The voltage causing
the electrical current to flow in the wire can be considered the water pressure at the faucet,
which causes the water to flow.
1. If we increase the pressure at the faucet, what happens to the amount of water
flowing in the hose?
2. If we use the water hose as an analogy to electricity, what happens if we increase
electrical pressure or voltage?
3. Using this same analogy, describe what happens if we remove the voltage source
(or turn off the faucet)?
72 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
MODEL 5: Power
1. Use the equation in Model 5 to define power.
2. What happens to power when voltage is decreased but current stays constant?
3. If voltage doubles what must happen to the current to maintain the same power?
73 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
MODEL 6: Drag is a drag.
Use the Model above to come up with some way to reduce drag. List at least 5 things to keep
in mind as you design your wind turbine blades.
74 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Protocol: Building the Most Efficient Turbine by Modifying Blade Design
Background:
Blade design and engineering is one of the most complicated and important aspects of
current wind turbine technology. Today engineers strive to design blades that extract as
much energy from the wind as possible throughout a range of wind speeds and gusts yet
are durable, quiet and cheap.
Materials:
3-4 Basic PVC wind turbines
1 crimping hub (per group)
Multimeter
3-4 Box fans
Rulers
Pictures of wind turbine blades
Wind speed meter
Blade construction materials: cardboard, balsa wood, tissue paper, plastic, paper cups,
index cards, Exacto knives, scissors, glue, tape, string, Knex, Legos, Tinker Toys, popsicle
sticks, toothpicks, hot glue guns
4” dowels (attach blades that you make to this)
PRELAB QUESTIONS:
1. What is the testable question?
2. What blade variables can you think of?
3. What blade variable will you test for in this experiment?
4. Describe how you will perform this experiment. Be SPECIFIC! (i.e., what materials
will you use, how many times will you test, how will you change your variable, how
will you record output?)
5. What is your hypothesis? What do you think will happen as you change your
variable?
75 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Protocol:
1. Build and test blades according to your experimental protocol
2. Share your results with peers
3. Refine your design to create an optimal set of blades incorporating these results
4. Test and evaluate your blades against those of your peers
Data Tally Sheet
Trial #
Variable
Voltage
Current
Power
(length,
(mV or V)
(mA or A)
= (V x A)
number, etc.)
(mW or W)
1
2
3
4
5
6
Graph your Data:
TITLE:
Power
Output
Units:
_____
Variable Tested:
76 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
POSTLAB Questions:
1. How did the voltage/current/power change as a result of manipulating your variable?
2. Do you think that your variable has a large or small effect on power production?
3. What was the optimal setting for the variable that you tested?
4. If you were a lead design engineer what would you recommend your company do to
their turbine blades? Why?
5. What problems did you encounter as you performed your experiments? What other
variable(s) was it hard to hold constant?
Wind Turbine Blade Competition
Details of the Task:
77 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
The Windy City Corporation needs a team of wind engineers to design and build a set of blades
for their new wind generator. These blades must be durable, quiet, and effective at converting
the energy of the wind into electrical energy.
Design Constraints:






Can use any materials found in the classroom resource area
Cannot use any manufactured blades or propellers
Blades cannot be more than 20” long
Blades must have no “sharp” points
You must keep track of the materials you use on your data sheet
You must test blades at least once before presentation time
Competition:
Each blade set will be tested at high and low wind speeds for 30 seconds. Power output when
your turbine is connected to a load will be calculated and averaged. The team with the highest
average output will be the winner.
Design Questions:

How many blades do you plan to place on your hub?

How long are you going to make these blades?

What materials are you going to use? Why?

After your first test what modifications did you make to the blades? Why?
78 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Final Design
How many blades:
________________________
Length of blades:
________________________
Width of blades:
________________________
What materials did you use to make your blades?
Sketch your blades from two viewpoints.
Individual Power Data:
High Wind Speed
Voltage:
Amperage:
Power Output:
Low Wind Speed
Voltage:
Amperage:
Power Output:
Average Power Output (High and Low):________________________
79 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Class Data:
Group
Blade
#
Materials
Length
(cm)
High
Speed
Power
Low
Speed
Power
Average
Power
1
2
3
4
5
6
7
8
9
10
80 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Conclusion:
1. Which blades seemed to perform the best?
2. Why do you think that they did well?
3. How would you change your blades to perform better?
81 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Additional Information for Building and Testing the Wind Turbine:
BUILDING THE PVC TOWER BASE for BASIC WIND TURBINE:
Instructions from KidWind.Org
82 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
83 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
84 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
85 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
86 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
How to Use the Multimeter
From KidWind.org
87 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Culminating Project
Why?
The goal of the culminating project is to assess if students know, what they know, and whether
they understand the content, concepts and processes discussed in this unit. In addition, the
assessment is designed to see how well they know and understand solar energy conversion and
uncover what they still do not know or understand. A performance task is a complex scenario
that provides students an opportunity to demonstrate what they know and are able to do
concerning this concept. We ask students to apply all that they have learned in this unit to an
authentic real life situation.
Using the GRASP Framework for Authentic Assessment of Learning
“To begin with the end in mind means to start with a clear understanding of your destination. It
means to know where you’re going so that you better understand where you are now and so
that that steps you take are always in the right direction.” –Stephen Covey
G
Goal: Provide a statement of the task; establish the goal, problem, challenge or
obstacle in the task.
R
Role: Define the role and/or job of the students in the task.
A
Audience: Identify the target audience within the context of the scenario (e.g.,
clients, committee, community members)
S
Situation: Set the context of the scenario; explain the situation
P
Products or Performances: Clarify what the students will create and why they will
create it
S
Standards/Criteria (to judge product or performance): Provide students with a clear
picture of success; issue rubrics or develop them with the students
88 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Wind Energy Expert Task:
Driving Questions:
How does renewable energy potential differ within a specific state and across the United
States?
How can we maximize the amount of wind energy captured?
How can we maximize the amount of wind energy transformed into electricity?
Goal
Apply knowledge of wind energy to develop a plan
for increasing efficiency of wind energy capture and
transformation
Role
Engineer for Windy City Corporation
Audience
Panel of Windy City Corporation business people and
scientists
Situation
Windy City Corporation is looking to create a new
wind farm in specific states across the United States.
You are being asked to determine how to maximize
wind energy captured and transformed into
electricity within a state. You must recommend a
location for the wind farm. Finally, you must test
your product to determine success of your model.
Performance/Product
Scientific Poster and Presentation of model. The
Poster will describe the scientific process for your
wind farm location and scale model. You must
present your proposal and the model to the Windy
Corporation panel for judging.
Standards/Criteria
See holistic scoring guide below for overall project
89 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Instructions for the Student:
Solar energy creates differences in air temperature, which causes wind. Wind energy varies
based on location, elevation and other land features. If we design and create a wind turbine
we can capture the wind energy and transform it into electricity. Your group has been provided
a specific state. Your task is to determine how to (1) maximize the amount of wind energy we
can collect, (2) maximize the transformation into electricity be designing an efficient turbine,
and (3) communicate how research on your specific location has informed your decisions. Your
designed device should take into account what you have learned about the effect of
topography, elevation and location on wind speed, the principle of lift force, and the efficient
transformation of mechanical energy from the wind into electricity.
Dimensions of the task:
Understandings:



Solar energy creates wind due to the uneven heating of the air
Wind energy is a renewable energy source which can be transformed to mechanical
energy of the blades and then transformed into electrical energy
Specific factors – including elevation, landforms, location, wind turbine design – impact
the efficiency of wind energy
Knowledge:
Skills:
Density
Apply knowledge of science and technology to
create a model to maximize wind energy
captured and transformed to electricity
Lift force
Wind speed and direction
Topography
Conduct the project, specifying the problem,
research, design, experimental process,
analysis of data, results and solutions
Wind turbine
Drag
Pitch
Electric circuit
Units of Measure: Volts, Amps, Watts
90 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Holistic Scoring Guide
Score
Description
5
Demonstrates complete understanding of the problem. All requirements
of task are included in response.
4
Demonstrates considerable understanding of the problem. All
requirements of task are included.
3
Demonstrates partial understanding of the problem. Most requirements
of task are included.
2
Demonstrates little understanding of the problem. Many requirements of
task are missing.
1
Demonstrates no understanding of the problem
0
No response/task not attempted
91 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
Student Names:
Science Poster Rubric
CATEGORY
Expert
Post Doc
Graduate Student
Undergraduate
Graphics Clarity
Graphics are all in
focus and the content
easily viewed and
identified from 6 ft.
away.
Most graphics are in
focus and the content
easily viewed and
identified from 6 ft. away.
Most graphics are in
focus and the content
is easily viewed and
identified from 4 ft.
away.
Many graphics are
not clear or are too
small.
Graphics Relevance
All graphics are related
to the topic and make it
easier to understand.
All borrowed graphics
have a source citation.
All graphics are related to
the topic and most make
it easier to understand.
All borrowed graphics
have a source citation.
All graphics relate to
the topic. Most
borrowed graphics
have a source citation.
Graphics do not
relate to the topic OR
several borrowed
graphics do not have
a source citation.
Labels
All items of importance
on the poster are
clearly labeled with
labels that can be read
from at least 3 ft. away.
Almost all items of
importance on the poster
are clearly labeled with
labels that can be read
from at least 3 ft. away.
Several items of
importance on the
poster are clearly
labeled with labels that
can be read from at
least 3 ft. away.
Labels are too small
to view OR no
important items were
labeled.
Content Accuracy
At least 7 accurate
facts are displayed on
the poster.
5-6 accurate facts are
displayed on the poster.
3-4 accurate facts are
displayed on the
poster.
Less than 3 accurate
facts are displayed
on the poster.
Knowledge
Gained
Student can accurately
answer all questions
related to facts in the
poster and processes
used to create the
poster.
Student can accurately
answer most questions
related to facts in the
poster and processes
used to create the poster.
Student can accurately
answer about 75% of
questions related to
facts in the poster and
processes used to
create the poster.
Student appears to
have insufficient
knowledge about the
facts or processes
used in the poster.
Attractiveness The poster is
exceptionally attractive
in terms of design,
layout, and neatness.
The poster is attractive in The poster is
terms of design, layout
acceptably attractive
and neatness.
though it may be a bit
messy.
Grammar/
Spelling
There are 1-3 mistakes
on the poster.
There are no mistakes
on the poster.
The poster is
distractingly messy
or very poorly
designed. It is not
attractive.
There are 4-6 mistakes There are more than
on the poster.
6 mistakes on the
poster.
Total
92 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010
SCORE
35
Wind Resources
1. Kid Wind: lots of teacher resources, videos, presentations, and curriculum.
http://www.kidwind.org/
2. Renewable Energy World – wind power
http://www.renewableenergyworld.com/rea/home/wind-power
3. National Renewable Energy Resources Laboratory: wind turbine testing center.
http://www.nrel.gov/
1. National Energy Education Development (NEED) Project, the best source for teaching
about energy
http://www.need.org/
4. Iowa Energy Center http://www.energy.iastate.edu/
5. American Wind Energy Association: Education link goes to NEED wind energy
curriculum. http://www.awea.org/
6. U.S. Department of Energy, Energy Efficiency & Renewable Energy - Wind and Water
Power http://www1.eere.energy.gov/windandhydro/
7. Wind with Miller is an excellent tutorial for adults and children.
http://guidedtour.windpower.org/en/kids/index.htm
8. New Mexico North American Wind Research and Training Center
http://www.mesalands.edu/wind/default.htm
9. This is a PowerPoint showing whole turbine being built from start to finish.
http://www.slideshare.net/mobear410/spearville-wind-farm
10. Texas renewable energy website. Very good lesson plans using Texas examples.
http://www.infinitepower.org/
11. Energy Information Administration - widespread information with interesting kid pages.
http://www.eia.doe.gov/kids/energyfacts/index.html
93 :: Developed by PARC & Science Outreach, with support from the Toshiba America Foundation::
Washington University in St. Louis, January 15, 2010