Homemade Sciencewith Bruce Yeany

Experiments  /  Solar Motor  /  Worksheets

Solar Motor: printable worksheets

Choose the sheet for the learner's age. Each prints on a single page. Build the project first, then fill it in together.

Ages 8-10: Predict, test & record
Name: ______________________Date: ____________

Homemade Science with Bruce Yeany · Solar Motor · Ages 8-10

Solar Motor Test Lab

Make a guess, test your solar motor, and record what happens.

1. Predict: when your drum sits in bright sunshine, it will...

◯ stay still◯ turn by itself◯ turn only if I keep pushing it

2. Count the turns in 15 seconds, then multiply by 4 to get RPM.

TryWhere the motor wasTurns in 15 sRPM

3. When I covered the top of the drum with cardboard, it...

◯ sped up◯ slowed down and stopped◯ kept going the same

4. A warm stretched strip gets...

◯ longer◯ shorter◯ no different

5. What did you find out about what makes the motor turn?

6. Why do you think the strips are black and not clear?

Ages 11-14: Explain & design your own test
Name: ______________________Date: ____________

Homemade Science with Bruce Yeany · Solar Motor · Ages 11-14

Is It Free Energy?

Use what you saw to explain the solar motor and test it fairly.

1. Fill in the energy chain: sunlight (light energy) -> ________ energy in the black strips -> ________ energy of the turning drum.

2. Explain why the drum turns. Use the words 'shrink' and 'center of gravity'.

3. If you warmed the whole drum evenly from all sides, it would...

◯ spin faster◯ not turn◯ spin backwards

4. Design a fair test of one change (for example: more or less light, mirrors, a covered half). Record your results.

TrialWhat I changedRPM

5. In your test, what did you change, what did you measure, and what did you keep the same?

6. The motor lifts 3 paper clips (weight about 0.03 newtons) up 0.5 meters in 20 seconds. Work = weight x height. Power = work / time. Find the work (joules) and the power (watts).

7. Someone calls this a 'free energy motor'. Is that true? Explain, and name one other machine that runs on sunlight.

Answer guide for grown-ups

Homemade Science with Bruce Yeany · Solar Motor · Answer guide

Answer guide

Ages 8-10: Solar Motor Test Lab

  1. Turn by itself (it may need one gentle push to start).
  2. Open answer: look for effort and careful observation.
  3. slowed down and stopped
  4. shorter
  5. Sunlight warms the strips on top; they shrink and make that side heavy, so the drum rolls and new strips come into the sun. No sun, no turning.
  6. Black soaks up more light and turns it into heat, so black strips warm and shrink faster than clear ones.

Ages 11-14: Is It Free Energy?

  1. thermal (heat); kinetic (motion)
  2. The strips on top absorb sunlight, warm up and shrink, pulling the cups slightly out of shape so the center of gravity moves above the axle on that side. Gravity rolls the heavy side down, bringing cool strips up into the light, and the process repeats.
  3. not turn
  4. Open answer: look for effort and careful observation.
  5. Example: changed the amount of light (mirrors or no mirrors); measured RPM; kept the same motor, time of day, position and counting time.
  6. Work = 0.03 N x 0.5 m = 0.015 J. Power = 0.015 J / 20 s = 0.00075 W (less than one thousandth of a watt).
  7. No. The energy comes from sunlight; the sunshine is free to use, but the energy is not created from nothing, and the motor stops without light. Other sun-powered machines: solar cells and solar calculators, solar ovens, radiometers, solar water heaters.