Day 8 - Potential and Kinectic Energy(To download a pdf of this lesson click here. You will need Adobe Acrobat Reader. Get it here free.) |
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Come Back Cans and Spool RacersNote: Have one Come Back Can prepared ahead of time with the outside of the can covered over so that the students cannot see how it works. Teacher information: In the spool racer activity, when you twist the rubber band, you are stretching the rubber band and storing potential energy (energy that can do work at some future time). The more you twist the rubber band, the more potential energy it has. As the rubber band unwinds, the potential energy changes into kinetic energy (energy of a moving object), making the spool turn and move forward. The Come Back Can activity has many of the same principles. When you do work by pushing the can, you give the can kinetic energy. Because the weight does not turn with the can. the rubber band winds up. Rubber bands store energy when they are stretched or twisted and release it later. The energy stored in the twisted rubber band is called elastic potential energy. This potential energy is released and returns to kinetic energy as the rubber band unwinds, rolling the can back to you. The can continues to roll back even after the rubber band is completely unwound. This is due to the can's inertia. This motion winds the rubber band in the opposite direction, again storing elastic potential energy, stopping the can again, and rolling it forward. This process continues until friction converts all the kinetic energy into thermal energy, and the can stops. Objectives:
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