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PBL Example: Solar Cars

August 2, 2011

I confess: I am a fan of solar energy.  At my former school my students and I retrofit a solar panel on a golf cart and made a Solar Gadget Charging Station.  I also did solar car projects.  I mean the small car kits you get for under $10 each.  You can get them from places like Kelvin and Pitsco.  I love these companies.  These are what I call real STEM supply companies.  (Places like PASCO are great, if you have an unlimited budget.  But everything is built for you already.)

In previous years I’ve done solar car projects with 6th, 8th, and 12th grades.  (The 12th graders worked together with the 6th graders.)  I was always a hit, and I’m thinking of doing one again this year.  But I don’t know if the students learned anything; I didn’t teach the classes – I just made the project happen.  So I got to thinking of details and how to make it better.

Students would work on groups of 2-3 and would get a set of common raw materials: solar panel, motor, pulley, etc.  They would have to construct a vehicle to some requirements/meet some challenges.  They would have to prepare a presentation (probably online) and present it to an audience (parents, teachers, etc.) and answer questions from “judges” orally.  Then I started thinking about the physics content — what could they learn?  Here’s what I came up with rather quickly:

  • Scientific Method: How are you using the SM in optimizing your car’s performance?
  • Measuring Skills: distance, mass, time
  • Energy Conversion: How many energy conversions can you find?  (start with nuclear)
  • Energy: Measure the KE of the car.  Debate solar as a renewable source.
  • Efficiency: How efficiently does the car use solar panel’s energy?  How efficient is the solar panel?
  • Electricity: What are the voltage – current characteristics of a solar panel?  What is the SP’s maximum power?
  • Electromagnetism: How does a motor work?
  • Thermal: How does soldering work?
  • Kinematics: Generate position-time and velocity-time graphs of cart (via video analysis)
  • Technology: digital data acquisition equipment, video analysis, website design
  • Engineering: building the cart, I guess.  Collaboration.
  • Machines: What is/are my transmission (pulley) ratios?
  • Dynamics: What forces act on the moving car when…?  What are the benefits & drawbacks of friction?
  • Rotational: (do “something” with the rpm of the motor?)
  • Modern Physics: What is the Photoelectric Effect?  How does relate to the SP?
  • Work and Power: What is the work done against gravity climbing a ramp? How powerful is your car?
  • Research: How have other’s made solar cars?  What worked well for them?  How does an electric car work?
  • Investigative Activity: How does the power from a solar panel (or speed of the car) depend on the area exposed to light?

I stopped there.  You might squeeze out some more.

Okay PBL and SBG experts out there:

Is this a worthwhile use of class time?  Could this be mated with a SBG format?

Please comment.

p.s. I get my DMMs from Kelvin too for under $3 each.  If you use these in your electricity unit, this is definitely the place to get them.


From → Thoughts & Ideas

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