Classroom Robotics – Science – Day 7 - Pg. 1
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Classroom
Robotics –
Science –
Day 7
Overview
Today, the students will learn about energy conversion by
using motors.
Workshop Objectives:
Students will be able to…



Understand energy conversion
Identify the flow of energy from one state to an other
Master concrete examples of the laws of thermodynamics
Suitable Ages: 11+
Time Needed: 1h 15min
In this packet
Facilitator’s Guide
Magic Smoke Worksheet
Magic Smoke Worksheet – Answer key
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FACILITATOR’S GUIDE
Activity Goal
Today, the students will learn about energy conversion by using motors.
Objectives
Students will be able to…



Understand energy conversion
Identify the flow of energy from one state to an other
Master concrete examples of the laws of thermodynamics
Materials

Two motors and a cable to connect them for
each group/student

Magic Smoke Worksheet
Set Up
Print enough worksheets for each student and get motors and cables out. If a robot is already built you
don’t need to take it apart as long as the motors can be connected together.
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Procedure
Time
10 min
Action
1. As an introduction, ask the students what they learned about
energy on the previous day. You can ask questions such as
“what kind of energy do you know?”, “what are the three laws of
thermodynamics?” etc. You can segway into today’s theme by
asking them if they know methods of converting energy from
one type to an other.
2. Have the students do the magic smoke worksheet.
30 min
20 min
10 min
3. You can work question 11 and 12 of the worksheet with the
students. If you have any resources with pictures you can show
them, you are encouraged to use them. Otherwise, you can just
talk about the fact that most energy sources use some sort of
device converting mechanical motion to electricity.
4. Have your students finish their worksheet if they haven’t done
so.
If your students are done, you can have them prepare their
robot for the next day by trying to attach sensors to it
(ultrasonic, touch and light sensors).
5. Clean up.
5 min
Materials Needed
Magic smoke worksheet
Two motors and a cable to
connect them for each group
Magic smoke worksheet
Robot
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Background Notes
Today we will expand on the definition of energy from yesterday.
We will discuss the formula for energy. The formula was identified through the hard work and experimentation of
dedicated scientists like Mme. Du Chatelet. They discovered that the formula for energy can be derived from Work
and the definition of Force as defined by Newton.
The experiment today will help them explore the laws of energy further and the ramifications of them. They will use a
motor connected to another motor to show how energy is convertible. Energy is easily converted from kinetic energy
to electric energy with a Dynamo. They will learn that a motor is a dynamo. When energy is put into a dynamo by
spinning it, electricity will be induced in a wire. This type of dynamo is called a generator. Most of the energy induced
in the wire by the dynamo can be transferred to another dynamo that will start to spin.
The second dynamo is called a motor which converts the electric energy back into kinetic energy. Not all the energy is
converted back to kinetic energy. The rest of the energy is not lost, however. According to the first law, the
conservation law, it cannot disappear. It is changed however into heat. Heat is a less organized energy and therefore
has more entropy. This makes sense with regards to the second law of thermodynamics, the entropy law. Hopefully
the students will recognize that when their motor stops running, or stalls, the electric energy is still flowing to the
motor. Because the energy is flowing to the motor but the motor cannot release it through kinetic energy, it will find its
way out through heat. That is why motors heat up, eventually melt and no longer work. Moral of the story is not to
allow the robot motors to stall for long.
The dynamo is a very interesting tool. The dynamo is responsible for almost all the electric energy we use today.
Inventors have found many interesting ways to use kinetic energy to create electric energy by simply spinning
dynamos. They have made a lot of money for many people as a result. Inventions and innovations like the dynamo
are what have made this country prosperous.
The students should be able to identify several ways that water, wind and steam are used to spin turbines. The
turbines are the spinning part of large dynamos that are at generator plants. The dynamos create the electricity that
we use in our houses to create light, heat, and run our appliances. They may be able to follow the energy even further
back to primary sources of energy. What causes the wind? (Sun heating the Earth)How did the water get into the
mountains? (Sun evaporating the water in the ocean) What makes the fuel for the steam? (Fossil fuels were ancient
plants that used the Sun’s light through photosynthesis to grow) Energy is conserved in many ways and can be stored
for centuries.
Whenever possible use the vocabulary words in conversation with the students and encourage them to use the
vocabulary words correctly when talking with you.
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Converting Energy and Magic Smoke
Name __________________________
Class _____________
Connect two of your motors with a wire as shown:
1. Place a wheel on each motor
2. Spin one motor
3. Determine how much the second wheel spins compared to the first by placing a mark on one axle of each wheel.
4. Repeat as long as it is fun
Questions:
1. What is the technical name for the motor you are spinning?
_____________________________________________________________________________________________
2. What type of energy is being created by spinning the Wheel and motor?
_____________________________________________________________________________________________
3. What type of energy is being produced in the other motor?
_____________________________________________________________________________________________
4. How much of the energy is being transferred from your fingers to the second wheel?
_____________________________________________________________________________________________
What law predicts this? Explain
_____________________________________________________________________________________________
5. Does the second wheel spin as much as the first?
_____________________________________________________________________________________________
What law predicts this? Explain.
_____________________________________________________________________________________________
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6. What happened to the energy? Explain.
_____________________________________________________________________________________________
7. What happens to the energy when you stall your servo motors on the robot?
_____________________________________________________________________________________________
Which law predicts what would happen to your robot? Explain.
_____________________________________________________________________________________________
8. Why is this bad?
_____________________________________________________________________________________________
9. What is the story of the Blue Smoke? What does it have to do with your motors?
_____________________________________________________________________________________________
10. What appliances in your house have motors? How can you smoke them? (do not try this at home!)
_____________________________________________________________________________________________
11. This simple demonstration shows you how most of our electricity gets to our houses. All you need to send
electricity to your house is to spin a generator. Can you think of ways that your utility company spins generators?
(hint: this is a very important resource for Texas)
_____________________________________________________________________________________________
12. Can you think of other ways that energy can be converted from one type of energy to another?
Chemical energy into electricity?
_____________________________________________________________________________________________
Solar energy into hot water?
_____________________________________________________________________________________________
Sound energy into electricity into sound energy?
_____________________________________________________________________________________________
Light energy into radio waves into light energy?
_____________________________________________________________________________________________
Others?
_____________________________________________________________________________________________
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Converting Energy and Magic Smoke
Name __________________________
Class _____________
Connect two of your motors with a wire as shown:
1. Place a wheel on each motor
2. Spin one motor
3. Determine how much the second wheel spins compared to the first by placing a mark on one axle of each wheel.
4. Repeat as long as it is fun
Questions:
1. What is the technical name for the motor you are spinning?
The motor is actually a Dynamo. A dynamo converts mechanical energy into electrical energy and vice versa. A dynamo
will create electrical energy as a generator when kinetic energy is put into it by spinning it. A dynamo will create kinetic
energy, spinning, when electric energy is put into it.
2.
What type of energy is being created by spinning the Wheel and motor?
The first wheel is spinning the motor with Kinetic energy, and electric energy is flowing out of it.
3.
What type of energy is being produced in the other motor?
Electricity is flowing into the second motor, and is therefore creating kinetic energy, spinning.
4.
How much of the energy is being transferred from your fingers to the second wheel?
All of it. All of the energy you are putting into the motor is being used by the system.
What law predicts this? Explain
First law of Thermodynamics, the conservation law. Energy cannot be created or destroyed.
5.
Does the second wheel spin as much as the first?
No
What law predicts this? Explain.
The second wheel does not spin at the same rate because some energy is being converted to heat in the friction between
gears and shaft spinning in the motor. The law that predicts that the second wheel will not spin the same amount is
Entropy, the 2nd law. Energy moves to a lower state. Heat is one of the lowest states of energy.
6.
What happened to the energy? Explain.
Some of the kinetic energy and electrical energy was converted to heat energy
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Classroom Robotics – Science – Day 7 - Pg. 8
7.
What happens to the energy when you stall your servo motors on the robot?
All of the electrical energy is converted to heat energy.
Which law predicts what would happen to your robot? Explain.
2nd Law, entropy will convert the kinetic energy to heat.
8.
Why is this bad?
If the robot overheats the wires inside the dynamo will melt and the motor will short out.
9.
What is the story of the Blue Smoke? What does it have to do with your motors?
Many engineers like to tell the story of the blue smoke. The blue smoke keeps the motor alive. If the blue smoke
escapes, the motor dies. This is just another way to describe what happens when a motor overheats. As it overheats the
overheated wires melt the insulation around them. As they melt, blue smoke is produced, if not fire. If all the isolation
melts on the wire, they will touch each other and short out the motor. When that happens the motor dies.. If you stall
your motor too long, the motor will heat up so much that the insulation around the wires will burn and this will short
your motor.
10. What appliances in your house have motors? How can you smoke them? (do not try this at home!)
Jam them or stall them or over work them. This often happens in vacuum cleaners when strings or other things get stuck
around the beater. Mixers may stall if you try to make bread dough in them. Electric drills will often cook when you try to
screw in a screw into a piece of very hard wood.
11. This simple demonstration shows you how most of our electricity gets to our houses. All you need to send electricity to your
house is to spin a generator. Can you think of ways that your utility company spins generators? (hint: this is a very
important resource for Texas)
Most utility companies in Texas use oil or coal that creates steam that rises through a turbine that spins and creates
electricity. Windmills can create energy. Dams can create Hydroelectric energy. Tides can produce energy.
12. Can you think of other ways that energy can be converted from one type of energy to another?
Chemical energy into electricity? Battery
Solar energy into hot water? Solar panel
Sound energy into electricity into sound energy? Microphone, or radio
Light energy into radio waves into light energy? TV
Others? Cars convert gasoline into kinetic energy.