E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Science as Inquiry: As a result of activities in grades 5-8, all students should develop
• Understanding about scientific inquiry.
• Abilities necessary to do scientific inquiry: identify questions, design an investigation, collect and interpret
data, use evidence, think critically, analyze and predict, communicate, and use mathematics.
Source: National Science Education Standards
NSES Standards for Grades 5-8:
NCTM Expectations:
Motions and Forces
•Collect data using observations, surveys, and
experiments.
•The motion of an object can be described
by its position, direction of motion, and
speed. That motion can be measured and
represented on a graph. Unbalanced forces
will cause changes in the speed or direction
of an object’s motion.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Science Process Skills:
•
•
•
•
•
Observing
Comparing
Inferring
Predicting
Communicating
Math Process Skills:
• Measuring
• Recording
• Analyzing
Objective:
The learner will specify the expected change in motion
caused by unbalanced forces acting on an object.
The learner will determine the faster fluids move, the
less pressure they exert.
Time: 40–60 Minutes
(Contingent upon the number of students and the stations
selected)
Materials: See each station description for list of
materials needed.
Materials for all
Stations:
Pencils
Station Cards
Student Activity Log
(one per student)
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Instructor Preparation :
See each station description for teacher preparation.
Students will work in pairs at each station. A designated pattern
for movement among the stations should be determined. Appropriate Task Cards and materials for conducting the experiments
should be placed at each station.
Note:
Time may not allow for all stations to be completed. Many
of the stations are similar and
Instructors may choose which
station to include for this lesson. It is not necessary to do
all nine stations. For example,
“Ping and Pong” and “Sticky
Papers” are very similar. If time
is limited, students could complete one of these activities.
Each station should be clearly marked to help students identify
their workstation and where to record data and answer questions
in their Activity Log.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Instructor Background Information:
Key Vocabulary
Airfoil—A shape of a wing
or blade (of a propeller, rotor or sail) as seen in crosssection.
Fluid—Substances that
flow freely and tend to
assume the shape of the
container in which they are
held.
Nonviscous—A true “nonviscous” fluid would flow
along a solid wall without
any slowing down because
of friction.
Nonturbulent—A term describing a streamlined flow
in which all particles move
at the same speed and in
the same direction.
Turbulent—A term describing a highly irregular form
of flow, in which a fluid
is subject to continual
changes in speed and
direction.
Hydrodynamics—The
study of water flow and its
principles.
Lift—The force that raises
an aircraft off the ground
and keeps it aloft.
Velocity—The rate of motion in a particular direction.
Daniel Bernoulli was an 18th century Swiss mathematician and
physicist known for his work describing the movement of fluids.
Bernoulli came from a family of mathematicians. Daniel’s father,
Johann, and his uncle, Jacob, made important contributions
to the fields of calculus and probability theory. Daniel was the
middle of three brothers, all of whom also pursued advanced
mathematics studies.
Of all of the members of this remarkable family, Daniel Bernoulli
could be considered to be the most gifted if numbers and prestige of prizes are used as a measure. On ten different occasions,
Daniel received the annual prize awarded by the French Academy
of Sciences. These prizes are outward signs of Daniel’s talent for
applying his gift for mathematics to the study of a wide range of
physical phenomena including planetary orbits, the movement
of tides, vibrating strings, and behaviors of fluids. It is this last
category of work for which he is probably most well known.
In 1738, when he was 38, Daniel published his work on fluids in a
book entitled Hydrodynamica. In it, he laid out the detailed mathematical descriptions of fluid movement that he had developed
earlier while a professor of mathematics at the University of St.
Petersburg in Russia where he began his professorship at age
25. (Bernoulli later joined the faculty at the University of Basel in
Switzerland, where he remained active as a scholar until his 80th
year, just two years before his death.)
From Daniel Bernoulli’s work, we are able to describe mechanics
of fluid motion in various settings. One particular relationship
known as Bernoulli’s Principle (sometimes referred to as the
“Bernoulli Effect”) has proved to have broad applications. This
principle (which is supported by a fairly complex equation) states
there is an inverse relationship between the velocity of a fluid (a
liquid or a gas) and its pressure – the greater the fluid’s velocity,
the lower the fluid’s pressure.
As with many models in physics, Bernoulli’s Principle is based on
equations describing ideal fluids, or fluids that are nonviscous,
incompressible (have a constant density), nonturbulent, and
steady.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Bernoulli’s Principle has a wide range of applications, from explaining why a spin applied to a baseball as it leaves the pitcher’s
hand results in a curved pitch to how air is pulled up and out of
a chimney. This principle also helps explain why aerodynamic lift
occurs as air flows over an airplane wing.
How an Airfoil Generates Lift
The relationship between Bernoulli’s Principle and the generation
of lift is one of the more popular teaching applications. Although
Bernoulli’s Principle is not the only factor at play when lift is
generated, airfoils do help demonstrate clearly the relationship
between increasing fluid velocity and decreasing fluid pressure.
As an air mass hits the leading edge of an airfoil, the mass of air
separates, with air flowing above the airfoil and air flowing below. The air moving above the airfoil moves faster (has a greater
velocity) than the air flowing beneath. As described by Bernoulli’s
Principle, the faster-moving air has a lower pressure than the
slower-moving air beneath the airfoil. The higher-pressure fluid
beneath the airfoil pushes upward, and the airfoil experiences lift.
A Common Fallacy of Lift
Unfortunately, a large number of sources provide an inaccurate
explanation of the physical basis for airplane lift. This has led to
widespread misconceptions about this phenomenon. Inaccuracy
in applying Bernoulli’s Principle to lift lies in the mistaken notion
that molecules of a fluid that separate from one another at the
leading edge of an airfoil will meet up again at the same time at
the trailing edge. The thinking continues that because the upper
surface of the airfoil is longer (typically curved) than the lower
surface, molecules traveling over the top surface must travel faster to meet up at the same time with the molecules passing under
the lower surface. But data show, in fact, that the fluid above an
airfoil is actually moving faster than necessary to keep pace with
the molecules moving beneath the airfoil. In other words, when
the molecules separate from one another at the leading edge
of the wing, the molecules that travel across the top of the wing
reach the trailing edge faster than their “counterparts” traveling
under the wing. The following figure supports this observation.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Experimental Observation
of Air Velocities Over and Under a Wing
50
70
air flow
10
30
50
70
time elapsed
from start
(milliseconds)
The general idea of lower pressure above the airfoil and higher
pressure below the airfoil due to differences in velocity is supported by evidence. The figure above shows a wing centered in a
wind tunnel with air moving from left to right. The colors represent bands of colored smoke applied in separate bursts at different times at the leading edge of the wing. For example, the red
smoke was applied first, the purple smoke second, the orange
smoke third, and the blue smoke last. At the instant shown in the
figure, the red smoke has traveled to the far edge of the wing 70
milliseconds after it was injected.
The figure shows several interesting things. The air molecules
traveling over the top of the wing moved at a much greater velocity than the air molecules traveling underneath the wing. The
relative positions of the two bands of red smoke represent this
relatively large difference in velocity. In addition, the staggered
positions of the bands clearly prove that the air molecules that
separate from each other at the leading edge of the wing do not
meet up again at the trailing edge. Interestingly, some scientists
argue that if the fluid molecules above the airfoil traveled only
fast enough to meet back up with same group of molecules, the
resulting pressure difference would not be large enough to generate adequate lift.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Lesson
Reminder Note:
Time may not allow for all stations to be completed. Many
of the stations are similar and
Instructors may choose which
stations to include. It is not
necessary to accomplish all
nine stations for this lesson.
Group students in pairs. Explain to students they will use the
Task Cards at each station to guide them through the procedures
they are to complete. Remind students that all data, observations
and answers should be recorded in their Activity Log. Explain the
movement pattern among stations and the expected student
behavior. Have students identify and proceed to their first station.
The teacher should monitor student movement and assist at
individual stations as needed. Some stations will require more
direct supervision. Pose applicable Strategic Questions to student
as they work at the stations.
This is a discovery lesson. Students will learn about Bernoulli’s
Principle and how concepts of fluid dynamics explain why an
airfoil creates lift. Students first move through a series of discovery stations and discover similarities when they compare areas
of faster moving fluids to areas of slower moving fluids. Students
will then apply this concept to explain lift.
Station: Computer Animation
Note:
All students must complete
all stations selected by the
Instructor. For example, if the
Instructor has selected 6 of the
9 stations, then all students
will complete 6 stations. If the
Instructor selects 8 stations for
this lesson, then all students
will complete 8 stations.
Station: Lift
Station: Wing It
Station: Ships in a Tank
Station: Level Climb
Station: Ping and Pong
Station: Paper Bridge
Station: Paper Tent
Station: Sticky Papers
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station:
Computer Animation
Materials:
• Computers
• Animation of fluid flow
in different pipe shapes
• Student Activity Log
• Pencil
Note:
This station needs direct
supervision. Students
may need assistance in
interpreting the graphs. You
may wish to point out to
students that “velocity” is how
fast something is moving and
in what direction it is moving.
Teacher Preparation
Load each computer with the animation found at:
http://home.earthlink.net/~mmc1919/venturi.html.
Activity
Students will experiment with moving the yellow squares or
“handles” to change the pipe shape. Graphs below the pipe
cutout view show the effect of pipe shape on velocity of the fluid,
fluid pressure, and flow rate. “Area” refers to the area of a cross
section of the pipe. Students are viewing a longitudinal section
of the pipe, not a cross section, but they can be guided to see the
relationship between a change in area and a change in pressure.
Explain to students that for this station, they will be examining
what happens to a fluid as it moves through pipes of different
shapes and sizes.
Students can choose a wide variety of shapes for the animation.
To focus their attention, the following shapes are suggested for
students to explore.
Shape
Title
Narrow pipe widens
“Rocket nozzle”
Wide pipe becomes narrower
Ask: What do you notice as you make a section of pipe wider?
Refer to curves below the animation for Pressure, Flow Rate, Area,
and Velocity. (Possible answer: The fluid flows more slowly; flow rate
does not change; velocity decreases; pressure slightly increases.)
Ask: What do you notice when you make a section of pipe narrower? Possible answer: The fluid flows faster; area decreases; flow
rate does not change; velocity increases; pressure decreases
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Strategic Questions:
1. What happens to the
fluid velocity when the fluid
moves from a narrow pipe
to a wide pipe? (Fluid velocity decreases.)
2. What happens to the
fluid pressure (as shown
on the graph below the
animation) when the fluid
moves from a narrow pipe
to a wide pipe? (Pressure
increases.)
What’s Going On?
In this activity, students explore the effect of fluid flow as they
change the dimensions of the pipe containing fluid. Below the
animated pipe is a graph showing the velocity, pressure, flow
rate, and cross-sectional area at each point in the pipe. These
are updated each time the student makes a change in the pipe
dimensions.
The animation shows that fluid velocity and pressure are inversely related. Each time a change is made that slows the fluid
velocity, the pressure of the fluid increases. When the fluid velocity is increased, the pressure decreases. The inverse relationship
between fluid velocity and pressure is clearly demonstrated.
3. Do you think this applies
for any pipe shape that
goes from a narrow start to
a wide ending? (Yes. Have
students try this.)
4. What do you think
happens if you reverse the
situation and go from a
wide start to a narrow end?
(The reverse happens. Pressure decreases and velocity
increases.)
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station:
Lift
Materials:
• Digital Scale
• Electric Blower w/dual
speeds
• Student Activity Log
• Pencils
• Dimension 3D Manufactured Base
• Dimension 3D Manufactured Airfoil
• Anamometer (windmeter optional)
Strategic Questions:
1. What change did you
observe in the scale reading when the air flow increased? (The scale reading
decreased.)
2. Why do you think this
change occurred? (An
upward force acted on the
airfoil to lift it. Therefore, the
scale did not register as great
a downward force by the assembly due to gravity.)
Teacher Preparation
This activity was designed and manufactured using the Dimension 3D Printer—you may download the airfoil and baseplate STL
file located on the DoD website. If you do not have a Dimension
3D Printer, please locate a site to print a base and airfoil for you.
Activity
This activity might be best handled by having an adult present
to explain to students how they will carry out this activity. Stepby-step procedures are provided on the Task Card for this station. After assembling the base plate and support rod, students
will measure the mass of the airfoil and support assembly. They
will alternately direct slow-moving and fast-moving air from the
electric blower at the leading edge of the airfoil and note in their
Activity Logs any changes in the reading on the scale. If desired,
an anamometer can be used to measure the speed of the air from
the electric blower, although this is not critical. Guide students
using the Strategic Questions.
What’s Going On
This activity tests the amount of lift that takes place at different
air velocities. Students observe that the scale reading for the
airfoil assembly decreases as they increase the speed of the air
blower directed at the airfoil. This demonstrates that the downward force due to gravity is being offset by an upward force due
to lift. The upward force increases with increasing air velocity. It is
important to emphasize to students that the mass of the object
does not change; mass is constant. What they are observing is
the change in forces on the object.
3. Which gives more lift:
slow-moving air or fastmoving air? (Fast-moving air
gives more lift.)
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station: Wing It
Teacher Preparation
Suggestion­—a Styrofoam block may be used as the base instead
of making the cardboard base.
Materials:
• Regular weight copy
paper
• 13 cm x 25 cm
corrugated cardboard
• Ruler
• Bamboo skewers (shish
kebab sticks, available
in grocery stores) or
knitting needles
• Clear tape
1. Build a base to use as wing testers.
a. With a 13 cm x 25 cm piece of corrugated cardboard, make
a fold at 5 cm, 10 cm, and 15 cm from the end.
b. Fold the cardboard into a box-like structure with open
ends shaped like a trapezoid with the widest edge on the
bottom.
c. Tape the structure together into this shape.
d. Make two dots 7.5 cm apart in the center of the top of the
cardboard base.
• Scissors
• Pencil
• Small electric fan or
hair dryer
e. Push the rods (skewers or knitting needles) through the top
of the base at the dots. Make sure that the rods are straight
with the ends secured in the bottom of the base to keep
them stationary.
• Cardboard, cardstock,
manila file folder or
heavy weight paper 10
cm x 15 cm or larger
f. Place the pencil-top erasers on the sharp ends of the skewers or knitting needles for safety.
• Pencil-top (cap) erasers
2. Make the wing
• Student Activity Log
Note:
a. Draw a line across a sheet of 21.5 cm x 28 cm paper, 15 cm
down from the top (so you have two unequal parts—one
15 cm x 21.5 cm and one 13 cm x 21.5 cm).
b. Make a light fold along the line--do not crease heavily.
Direct supervision is advised.
c. Bring the corners of the paper together, causing the longer
side to arch. Tape the ends of the paper together. The wing
should have a gentle curve on the upper surface.
d. Line up the wing over the rods on the base and mark where
the rods should protrude through. With the pencil, poke
holes through the paper both the upper and lower sides of
the wing—the holes should be big enough for the yellow
part of the pencil to fit through.
3. Set the fan on the table.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
4. Anchor the base in front of the fan. It can be taped or anchored
with a book.
5. Remove the erasers, and slide the wing all the way down the
rods to the cardboard base. Replace the erasers. The wing
should be curved on the top and flat on the bottom. You may
choose to experiment with different positions.
Activity
Explain to students how they will carry out this activity, demonstrating as appropriate. Explain that they will use a fan or hair
dryers to blow a fast, steady stream of air at the improvised wing
and make observations of the results. Then they will use a card to
block the air flow and observe how the wing moves in response.
Remind students to record their observations in their Activity
Logs.
What's Going On
The shape of an airplane wing helps create the force necessary to
lift an airplane into the air. Airplane wings are specially designed
to provide the upward force called lift.
Air molecules travel faster over the long top of the wing. When
the molecules move faster over a greater distance, they are more
spread out (less dense). When molecules move, they put pressure on whatever they strike. The more molecules that strike the
object, the more pressure or force there is on the object. Because
there are more air molecules per centimeter along the bottom
of the wing, the pressure of the molecules hitting the bottom of
the wing is greater than the pressure from the less dense layer of
molecules on the top surface of the wing. This pressure difference
causes the wing to be pushed or lifted upward.
Daniel Bernoulli developed the physical principle that describes this phenomenon in 1783. He discovered that increasing the velocity of a gas (or liquid) would lower its pressure.
Thus, most airplane wings are designed to take advantage of
air pressure differences.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station:
Ships in a Tank
Materials:
• Aquarium fish tank or
other large container
for holding water
• Water fountain pump
• Rubber tubing
• Nozzle adapter
• GFCI power strip
Teacher Preparation
1. For safety reasons, a GFCI extension cord should be used.
2. Attach nozzle to water outlet using approximately 2 cm of
plastic tubing.
3. Tape pump to inside of aquarium, centered as shown in the
photo.
4. Fill the aquarium to make sure the nozzle on the pump is 1/2
centimeter under the water and not on the water surface.
5. If boats are made out of wood, coat them with water-proofing
or paint.
• String
6. Attach the eyelet to the bow of the boat.
• Coffee stirs approx 20
cm long
7. Thread the string through the coffee stir and place the coffee
stir so that it floats on top of the water surface over the nozzle
opening – see diagram. Tape one side of the string down to the
side of the tank. Now thread the eyelets that are attached to
the bow of the boats through the coffee stir. Tape the string to
the other side of the tank.
• Tape, black electrical
• Paper towels
• Two small toy boats
with eyelets attached
at the bow – wooden
boats work best
• Pencil
• Student Activity Log
Activity
Explain to students how they will carry out this activity. Be sure
that students make and record their predictions before they begin the activity. Instruct students to begin only when the water is
calm and the boats are positioned correctly. Remind students to
record their observations in their Activity Logs.
What’s Going On
Bernoulli’s Principle is illustrated by the direction of movement to
the two boats in response to the flow of water. When the pump is
turned on, it creates a fast-moving flow of water in between the
two boats. The water surrounding the boats moves much more
slowly. This creates an area of low pressure in between the boats
and the two boats move in the direction of this low pressure.
This phenomenon must be considered by naval vessels that need
to come into close contact while they are moving. Two ships
involved in “underway replenishment”, a method of ship-to-ship
transfer of cargo, provide a real world example. In an underway
replenishment maneuver, two ships drive along side each other
at close distances. The curved sides of the ships form a nozzle
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Note:
Direct supervision is advised.
that results in an increase in velocity of the water flowing between them. This increased water velocity results in decreased
water pressure between the two ships, causing the ships to tend
to drift toward one another. The ships need to be steered very
carefully in order to compensate for these changes in water pressure.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station:
Level Climb
Materials:
• Modified straws, 1 per
student (straws need to
be transparent to see
level of water)
• Water
• Student Activity Log
• Pencil
Strategic Questions:
1. Did the water level in the
straw change? (Yes, it moved
up the straw.)
2. Why do you think this
change occurred? (An
upward force acted on the
water to cause it to move
upward.)
3. If you think about a
house chimney like the
straw in this activity, how
would a strong gust of wind
blowing across the top
of the chimney affect the
air in the fireplace below?
(Fast-moving air will create
an area of low pressure at the
top of the chimney and cause
the air in the fireplace below
to move up the chimney.)
Teacher Preparation
1. Snip the straws with a pair of scissors making sure you do not
cut fully through the straw. The cut needs to leave a small
piece of straw intact so that after the cut, the two halves stick
together. The piece that attaches the two straws needs to be
flexible.
2. Fill glasses 1/3 full of water.
Activity
This activity might be best handled by having an adult present to
explain to students how they will carry out this activity and demonstrating as appropriate. Explain that they will place a straw in
the glass and bend the sections of the straw to form a right angle.
Emphasize to students that they should use a fresh straw, not one
that has been used by another student. They will blow through
the straw mouthpiece in the horizontal portion and observe the
liquid level in the vertical portion. Remind students to record
their observations in their Activity Logs. Guide students using the
Strategic Questions.
What’s Going On
As students blow air through the horizontal straw section, they
created a fast–moving blast of air. This moving air creates a region of lower pressure centered above the vertical straws opening. The surrounding air presses down with the same pressure on
the exposed liquid surface in the glass but the pressure at the top
of the straw decreases.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station:
Ping and Pong
Teacher Preparation
1. Tape one ping pong ball to each 20.0 cm length of string
2. Tape the other end of the pieces of string to the ruler 6.0 cm
apart.
Materials:
• 2 Ping Pong balls
• Tape
• Two 20–cm lengths of
string
• Ruler or meter stick
• Student Activity Log
• Pencils
Note:
Inflated balloons can be used
instead of ping pong balls. If
you have a drafty room, add a
little water before inflating the
balloons. This will help stabilize them. Lengths of string
will need to be increased. With
balloons, a meter stick may
work better than a ruler.
Activity
Explain to students how to carry out this activity, demonstrating
as appropriate. Show them how they will hold the ping pong
balls and ruler about 20.0 cm in front of their mouths. Tell them
that before they carry out the procedure, they will need to predict what will happen when they blow air at the ping pong balls.
Then describe how students will blow an airstream at the gap
between the two balls. Remind them to record their observations
in their Activity Logs.
What’s Going On
Most students will predict that the ping pong balls will move
apart as the air pushes between them. The balls don’t separate,
however. Instead the balls act as if they are attracted to each
other. The airstream that moves between the balls has lower
pressure than the surrounding air. This difference in pressure
causes the surrounding air to push inwards on the stream. The
ping pong balls are pushed into the lower pressure area.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station:
Paper Bridge
Teacher Preparation
1. Place the piece of paper on top of the two books so the ends
of the paper rest on the edge of each book.
2. Secure only one side with tape.
Materials:
• One 21.5 cm x 28 cm
piece of paper
• Two large books or
other objects at least
5.0 cm thick
• Straws (one per student)
• Student Activity Log
Activity
Explain to students how they will carry out this activity, demonstrating as appropriate. Describe how they will use a straw to
blow a fast, steady stream of air underneath the suspended piece
of paper. Remind students to record their observations in their
Activity Logs.
What’s Going On
As the student blows a steady stream of fast-moving air underneath the paper bridge, a difference in air pressure is produced.
The higher pressure on top of the paper pushes the paper into
the lower pressure area.
• Pencil
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station:
Paper Tent
Teacher Preparation
1. Fold a piece of paper lengthwise.
2. Set folded piece of paper on a flat surface like a pup tent.
3. Secure one side only with tape.
Materials:
• One 21.5 cm x 28 cm
piece of paper
• Straws (one per student)
• Tape
• Student Activity Log
• Pencil
Activity
Explain to students how they will carry out this activity, demonstrating if necessary. Describe how they will use a straw to blow
a fast, steady stream of air underneath the paper tent. Remind
them to record their observations in their Activity Log.
What’s Going On
Students might expect to see the paper move in an upward
direction. However, the rapidly moving air underneath the paper
creates an area of lower pressure than that of the surrounding air.
The “tent’ falls or flattens slightly as a result.
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Station:
Sticky Papers
Teacher Preparation
Set up the station with two strips of paper for each student.
Activity
Materials:
• 2 pieces of paper for
each student
• Student Activity Log
• Pencil
Explain to students how they will carry out this activity, demonstrating if necessary. Describe how they will hold one strip of paper in each hand at the level of their forehead. The strips of paper
should be parallel to one another flat sides facing and pointed
away from the student’s face. With the pieces of paper oriented
this way, students should blow air in a steady fashion between
the strips of paper and observe how the paper strips move in
response to the air flow. Remind students to record their observations in their Activity Logs.
What’s Going On
Students will likely predict that the pieces of paper will be
pushed apart by the air moving between them. If students direct
an airstream at the gap, however, the strips of paper will move
toward each other due to the creation of a low pressure area
between them.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Completion of Station Rotations
All students return to their group tables. Class discussion follows.
Sample Class Discussion Questions
Ask:
In what direction did you expect the two paper strips to move?
(away from each other)
In what direction did they move? (toward each other)
Note:
Many of the activities are
quick and easy to repeat in
front of the class as a way to
remind students about their
earlier experiences.
How did you change the air between the strips of paper? (by
blowing)
Did the air move/flow faster when you blew hard or soft? (the
harder you blew, the faster the air flowed)
How did the behavior of the papers change as you changed how
the air was flowing? (the harder you blew, the closer the papers
moved toward each other)
Flowing air has a lower pressure than stationary air. What evidence did you see of a change in air pressure? (paper strips moved
even though you weren’t blowing directly on them)
In these experiments, did the objects move toward or away from
the faster-moving fluid? (toward the faster-moving fluid)
Relate Bernoulli’s Principle to Airfoil and Lift
Explain: A wing is very effective at changing the speed of the
air as it flows along the wing’s upper and lower surfaces. The air
above the wing moves at a higher velocity than the air below the
wing. Bernoulli’s Principle states that air moving at high velocity
is lower in pressure than air moving at low velocity. Air passing
above and below the wing does not do so in equal time.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Strategic Questions:
Explain why some shower
curtains are pulled into the
shower when the water is
flowing out of the showerhead. (A low-pressure area
is created where the water
is flowing out of the shower
head. The shower curtain
is in a high-pressure area. If
the material of the curtain is
lightweight, it will move to
the low-pressure area.)
Draw or project a sketch of an airfoil on the board. (see sample
below)
Discuss with students as you draw and label your sketch. This is
an opportunity for students to apply what they learned during
the activities.
On the cross section of the wing, label the following:
Indicate the airflow above and below the wing with arrows.
Label the faster-moving air above the airfoil with the word faster.
Label the slower-moving air below the airfoil with the word
slower.
Label the low pressure area above the airfoil with the word low
pressure.
Label the high pressure area below the airfoil with the word high
pressure.
Draw an arrow pointing up and label it with the word lift.
Faster
Low Pressure
Air Flow
Slower
High Pressure
Lift
Conclusion
Guide students to generalize that in each activity the objects
moved toward the faster-moving fluid because the faster–
moving fluid had lower pressure.
The faster the fluid flows, the lower the pressure goes.
Objects tend to move from areas of high pressure toward areas of
low pressure.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Fluid Mechanics & Aerodynamics Activity
Activity Log
Station: Computer Animation
1. What do you notice as you increase the width of a section of the pipe?
___________________________________________________________________
2. What do you notice when you decrease the width of a section of the pipe?
___________________________________________________________________
3. Draw two pipes showing how you changed the fluid flow. Explain how the velocity
and pressure changed in each case.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Station: Lift
Blower Off
Blower Slow Speed Blower High Speed
Digital Scale
Reading
1. How did the scale reading change as you increased the blower speed?
___________________________________________________________________
2. Explain your observations.
___________________________________________________________________
___________________________________________________________________
3. Were you surprised by the changes you observed? Explain.
___________________________________________________________________
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Fluid Mechanics & Aerodynamics Activity
Activity Log
Station: Ping and Pong
1. Predict what will happen when you blow a steady stream of air between the two
ping pong balls.
___________________________________________________________________
2. What actually happened?
___________________________________________________________________
3. Why do you think the ping pong balls moved the way they did?
___________________________________________________________________
Station: Paper Bridge
1. Predict what will happen when you blow a steady stream of fast air underneath the
paper bridge.
___________________________________________________________________
2. What actually happened?
___________________________________________________________________
3. Why do you think the paper reacted that way?
___________________________________________________________________
Station: Wing It
1. What happened to the wing when the fan was turned on?
___________________________________________________________________
2. What happened to the wing when the flow of air was blocked by the card?
___________________________________________________________________
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Fluid Mechanics & Aerodynamics Activity
Activity Log
Station: Level Climb
1. What happens to the liquid as you blow into the horizontal straw?
___________________________________________________________________
2. Why do you think this happens?
___________________________________________________________________
Station: Ships in a Tank
1. What is your prediction?
___________________________________________________________________
2. What happens when the water flow between the boats is increased?
___________________________________________________________________
3. Why do you think the boats moved the way they did?
___________________________________________________________________
Station: Paper Tent
1. What do you expect to happen?
___________________________________________________________________
2. What happens when you blow air under the tent?
___________________________________________________________________
3. Why do you think the tent moved the way it did?
___________________________________________________________________
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Fluid Mechanics & Aerodynamics Activity
Activity Log
Station: Sticky Papers
1. In what direction did you expect the two papers to move?
___________________________________________________________________
2. In what direction did they move?
___________________________________________________________________
3. Did the air move/flow faster when you blew hard or soft?
___________________________________________________________________
4. How did the behavior of the papers change as you blew hard and then soft?
___________________________________________________________________
___________________________________________________________________
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Fluid Mechanics & Aerodynamics Activity Key
Activity Log
Station: Computer Animation
1. What do you notice as you increase the width of a section of the pipe?
Answers will vary. Students may notice that the velocity of the particles slows down and that the pressure
increases.
2. What do you notice when you decrease the width of a section of the pipe?
Answers will vary. Students may notice that the velocity of the particles speeds up and that the pressure
decreases.
3. Draw two pipes showing how you changed the fluid flow. Explain how the velocity
and pressure changed in each case.
Answers will vary depending on what shapes the students create.
Station: Lift
Blower Off
Blower Slow Speed Blower High Speed
Digital Scale
Reading
1. How did the scale reading change as you increased the blower speed?
The reading on the scale decreased as the blower speed was increased.
2. Explain your observations.
The assembly was lifted farther into the air as air speed was increased. This meant that it was not putting
its full weight on the scale.
3. Were you surprised by the changes you observed? Explain.
Most students will not be surprised. They will be able to visualize this result ahead of time.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Fluid Mechanics & Aerodynamics Activity Key
Activity Log
Station: Ping and Pong
1. Predict what will happen when you blow a steady stream of air between the two
ping pong balls.
Most students will predict that the balls will move away from each other.
2. What actually happened?
The balls moved closer together.
3. Why do you think the ping pong balls moved the way they did?
The change in air flow created a force that made them move together.
Station: Paper Bridge
1. Predict what will happen when you blow a steady stream of fast air underneath the
paper bridge.
Most students will predict that the paper will move upward.
2. What actually happened?
The paper dropped down slightly into the space between the books.
3. Why do you think the paper reacted that way?
The change in air flow created a force that made the paper move in a downward direction.
Station: Wing It
1. What happened to the wing when the fan was turned on?
The wing moved up the assembly.
2. What happened to the wing when the flow of air was blocked by the card?
The wing moved back down the assembly.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Fluid Mechanics & Aerodynamics Activity Key
Activity Log
Station: Level Climb
1. What happens to the liquid as you blow into the horizontal straw?
The liquid moves up the straw.
2. Why do you think this happens?
A change in forces on the liquid and the top of the vertical straw made it move.
Station: Ships in a Tank
1. What is your prediction?
Answers may vary. Most students will predict that the boats will stay in the same place.
2. What happens when the water flow between the boats is increased?
The boats are drawn together.
3. Why do you think the boats moved the way they did?
Answers may vary. Students may be aware that a new force developed that made the boats move together.
Station: Paper Tent
1. What do you expect to happen?
Answers may vary. Most students will be surprised that the paper drops. They expect the paper to move
up, not down.
2. What happens when you blow air under the tent?
The tent falls.
3. Why do you think the tent moved the way it did?
A new force was created by the moving air that made the paper move.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Fluid Mechanics & Aerodynamics Activity Key
Activity Log
Station: Sticky Papers
1. In what direction did you expect the two papers to move?
Most students will expect to see the papers move away from one another.
2. In what direction did they move?
The papers moved together.
3. Did the air move/flow faster when you blew hard or soft?
The air moved faster when I blew hard.
4. How did the behavior of the papers change as you blew hard and then soft?
The papers moved closer together the harder I blew.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Computer Animation
Complete this station with a teammate.
1
2
3
CHANGE the shape of the pipe by clicking and dragging the
yellow squares or “handles.”
Look at the how the pressure, flow rate, and velocity are
affected by the pipe shape.
ANSWER the questions in your Activity Log.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Lift
Complete this station with a teammate.
1
2
Assemble base plate and support rod.
3
Place airfoil on support assembly and weigh. Place entire assembly on the scale and record the scale reading in
Activity Log.
4
Position blower at leading edge of airfoil and direct slow
speed airstream over the wing.
5
Note any change in the scale reading and record data in
Activity Log.
6
Position blower at leading edge of airfoil and direct fast
speed airstream over the wing.
7
Note any change in the scale reading and record data in
Activity Log.
8
Answer remaining questions in the Activity Log.
Turn on digital scale, set scale to measure grams, and zero.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Wing It
Complete this station with a teammate.
1
2
Turn on the fan and observe the wing for 15-90 seconds.
3
This time, when the wing is halfway up the rods, hold a
card in front of the wing to block the wind from the upper
surface.
4
5
6
Try to block the wind in different ways.
Record your observations in your Activity Log.
Observe for 15-90 seconds.
Answer remaining questions in the Activity Log.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Ships in a Tank
Complete this station with a teammate.
1
2
Predict what will happen to the two boats when you turn
on the pump.
Write your prediction in your Activity Log.
3
Make sure the boats are centered and that the bow of each
boat is facing the water outlet.
4
Make sure the water is calm and boats are not moving
before you turn on the pump.
5
6
Turn on the pump and observe movement of the boats.
Record observations in your Activity Log.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Level Climb
Complete this station with a teammate.
1
Place the modified straw in the glass with water.
2
Bend the two sections of the straw so they form a right
angle.
3
Blow through the horizontal straw mouthpiece.
4
Observe the level of the liquid in the vertical section.
5
Answer questions in your Activity Log.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Ping and Pong
Complete this station with a teammate.
1
2
Hold the ping pong balls and ruler about 20 cm in front of
your mouth.
Make a prediction and write it in your Activity Log. If you
blow an airstream directly at the gap between the two
balls, how will the balls move?
3
Blow a steady stream of air between the two balls.
4
Answer remaining questions in your Activity Log.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Paper Bridge
Complete this station with a teammate.
1
Predict what will happen when you blow a steady stream
of fast air underneath the paper bridge and write it in your
Activity Log.
2
Use a straw to blow a steady stream of fast air underneath
the suspended piece of paper.
3
Answer remaining questions in your Activity Log.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Paper Tent
Complete this station with a teammate.
1
Use a straw to blow a steady stream of fast air underneath
the paper tent.
2
Answer questions in your Activity Log.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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Station Task Card: Sticky Papers
Complete this station with a teammate.
1
2
Hold both ends of two paper strips sideways by their ends
– one in each hand. The strips should be about 7 centimeters apart. Your hands should be forehead level. Blow
steadily between the strips of paper.
Answer questions in your Activity Log.
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Fluid Mechanics & Aerodynamics Assessment
Suggested Final Assessment Questions
1. Name 3 fluids.
2. According to Bernoulli’s Principle, how does the pressure of
a fluid change if its velocity increases?
3. In which direction do objects tend to move in a flow of air toward areas of high pressure or toward areas of low
pressure?
4. When and why does lift occur?
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Fluid Mechanics & Aerodynamics Assessment Key
Suggested Final Assessment Questions
Knowledge
1. Name three fluids.
Possible answer: Three fluids might be: air, water, juice.
Comprehension
2. According to Bernoulli’s Principle, how does the pressure of
a fluid change if its velocity increases?
Possible answer: If a fluid’s velocity increases, its pressure
decreases.
Analysis
3. In which direction do objects tend to move in a flow of air toward areas of high pressure or toward areas of low
pressure?
Possible answer: Objects tend to move in the direction of low
pressure.
Application
4. When and why does lift occur?
Possible answer: Lift occurs when the air pressure underneath
an object is higher than the air pressure above the object. The
difference in air pressure causes the object to move in the direction of lower pressure. This results in lift.
E3.1.1.1. Physics: B. Fluid Dynamics & Aerodynamics
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E3.1.1.1. Physics: B. Fluid Mechanics & Aerodynamics
Activity: Bernoulli’s Principle Experiments
Resources:
http://http://home.earthlink.net/~mmc1919/venturi.html
http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
http://www.av8n.com/how/htm/airfoils.html
http://www.maths.tcd.ie/pub/HistMath/People/Bernoullis/RouseBall/RB_Bernoullis.html
http://www.scienceclarified.com
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