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Exploring Energy Transformations
Name _____________________
Guided Inquiry Worksheets: The purpose of these worksheets is to provide a framework of questions to get
students to review what they already know, learn new content, and apply their understanding to the speedboat
contest. The answers are not expected to provide as much detail as is shown here, nor are they expected to be
correct in all aspects; however, the answers should be reasonable and justified. The students communicate with
the four Cs. Their answers should be correct, complete, concise, and clear. The answers should include words,
diagrams, and equations as are appropriate. These are collected after the class and returned, marked, at the start
of the next class to provide guidance.
Materials: Each group should have a variety of motors, batteries, voltmeter, and a couple of alligator clips. A
couple of water bottles with holes on the side should be demonstrated before the first question. The open-inquiry
at the end will also require purchased propellers, a weigh scale, and ping pong balls suspended by two long
threads to use as a quantitative test of air power.
1) The batteries provide energy to the boat, E = I V t. Name each variable and explain what it means using a
water bottle with holes on the side as an analogy.
Whiteboard Discussion Question: This is an example of a question that should be discussed in small groups and
answered on a whiteboard which is a great tool for assessment for learning and as learning. The whiteboard
provides evidence and a focus for their discussion, shows their present understanding, and demonstrates their
ability to communicate their understanding.
These electrical terms should be a review from grade9 or the present course (SPH 3U or SPH4C).
V
This is the volts, voltage, or most formally, the potential difference. It is labelled on the batteries and
is measured in volts. Most of the batteries are single cells and they provide 1.5 V. The 9-V battery is made of
six cells and provides 6 x 1.5 V = 9 V. The potential difference is the amount of energy given to the charges.
More voltage is like a water bottle with more water above the hole. (Volt = Joule/Coulomb, V = J/C)
I
This is the current and it is very similar to what we mean by the current of water. More current is like
a water bottle with larger holes. It is measured in amperes. (Amperes= Coulombs/second, A = C/s).
t
This is the time, measured in seconds. The current multiplied by the voltage, gives the power. When
the power is multiplied by time, it gives the electrical input energy. More time is provided by a larger water
bottle – just like a C cell will last longer than a AAA battery. Energy is measured in joules. (Joules = Volts x
Amperes x seconds = Joules/Coulomb x Coulomb/second x second)
2) How can you increase the electrical energy input by your choice of battery? Hint: Consider the number of
batteries and the type.
 If you choose just one battery, you should choose the one with the highest voltage, i.e., the 9-V battery.
 You can provide a higher voltage by connecting the batteries in series so that the voltage adds.
 You should also choose a battery that can provide enough current for the motors. Tell the students that
the watch batteries can’t do this, and they shouldn’t waste money on these. The D cells can provide the
most current for the longest time, but all of the other batteries can provide sufficient current.
3) How can you increase the kinetic energy output by your choice of motor?
Some motors have less electrical resistance and less internal friction than others and will be more efficient at
transforming the electrical energy into kinetic energy. This is why the really good - but expensive - motors are
not allowed. Motors can be inspected by turning the axle and discarding any that don’t turn easily. Noisy
motors should be rejected. The final motor choice will be made by testing the motors with propellers on them.
4) Why is one AAA a better choice than one AA, C, or D? The AAAs:
A) have less mass
B) have less resistance C) have more voltage D) can produce more current
Explain:
Multiple-choice concept questions: This is an example of a multiple-choice concept question. These questions are
provided to stimulate focussed discussions. They are an assessment for learning and as learning. (Later, they can
be used for assessment of learning.) To be most effective, you should first give students a chance to answer the
question on their own. Then have them show you their answers using small booklets with a large letter on each
page. If there is a lot of confusion, you might provide clarification by suggesting a diagram, everyday example,
key concept that will help. If almost everyone has the right answer, select a couple of students to explain the right
answer. If there are many right answers, you should provide a chance for them to discuss their answers and
rationale with their neighbours. They should be able to say why an option is wrong or right but irrelevant or right
but incomplete or correct and most important.
A) They have less mass. The batteries will be carried on board the boat and the more mass they have, the
slower the boat will go. Option B) may or may not be true but the internal resistance of the battery is not very
important. Option C) is false. The voltages are all 1.5 V. Option D) is false. They have a lower current limit not
higher, because they are smaller.
5) What advantage do the 9-V batteries have over the AAAs? The 9-V batteries have
A) more voltage
B) less mass
C) more voltage/mass
D) more mass/voltage
Explain: C) If you dissect a 9-V battery, you will see that it is made of six 1.5-V batteries with a similar, but
slightly smaller, mass than six AAAs. Furthermore, the 9-V battery has fewer connections that could come
loose. Options A) and B) are both true if you are comparing just one battery – but you are allowed to use
more than one, so this is not a useful comparison. D) This is backwards. They have slightly less mass per
voltage. Every team should use 9-V batteries. If allowed, they should try using more than one.
6) The electrical energy is converted to kinetic energy, E = ½ mv2. Explain clearly what each variable stands for.
This should be a review.
m
This is the mass of the moving object (kg).
v
This is the velocity of the object (m/s).
E is measured in Joules, defined to be one kg m2/s2.
7) As the boat runs, electrical energy is converted to kinetic energy, V I t = ½ mv2. Explain why the boat should
go faster and faster. Refer to the equations of questions #1 and #6.
As time goes on, the left side gets bigger because t increases; therefore, the right side should get bigger.
Mass is constant, so that means that the speed should increase.
8) It turns out that the boats will only accelerate for the first fraction of a second and then they will move at a
constant velocity. Where does the electrical energy go once the boat stops accelerating?
It mainly goes into kinetic energy of the air and water. There will also be some energy loss to sound and heat.
9) Examine the motors using one, two, and three 9-V batteries. Which motor and battery combination do you
think is the best choice? Explain why. Provide numbers to support your answer.
 This last question provides the students with an opportunity for open inquiry. They need to decide what
questions to ask and how these questions can be answered.
 The best motor should be light and able to push the ping pong ball a set distance away. These two needs
are in conflict. The results should be presented in a table and some measure of air power/mass should be
calculated.
 Note: The motors will be destroyed by overheating if too many batteries are used. These motors should
be able to handle several 9-V batteries without over-heating. Warn students to cautiously feel the motor
casing to check.