Power
Energy and Thermal Physics

Power cycling up a hill

Practical Activity for 14-16 PRACTICAL PHYISCS

Class practical

Measuring the power used in cycling uphill.

Apparatus and Materials

None listed

Health & Safety and Technical Notes

This must be done in a safe place, such as the school grounds.

Read our standard health & safety guidance


Procedure

  1. Students time themselves cycling up a rise.
  2. Determine the vertical distance climbed from an appropriate map or using a handheld GPS device. Alternatively, estimate the height with a sighting pole, a plumb line, and a large cardboard protractor.
  3. Knowing their own weight and estimating that of their bicycle, students calculate the output of useful power.

Teaching Notes

  • Useful power is calculated from:
    • Useful power = energy transferred/time taken = (total weight in newtons x height rise)/time taken
    • The mass of a bicycle is very unlikely to be less than 5 kg nor more than 20 kg . 10 kg would be an acceptable estimate, particularly as the mass of the student is probably of the order of 70 kg.
  • This experiment could be set as a class activity if a suitable site is available.

This experiment was safety-tested in January 2006

Power
appears in the relation P=VI P=I^2R P=V^2/R ΔQ=PΔt
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