# Power cycling up a hill

##### Class practical

Measuring the power used in cycling uphill.

None listed

#### Health & Safety and Technical notes

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

#### Procedure

a Students time themselves cycling up a rise.

b 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.

c Knowing their own weight and estimating that of their bicycle, students calculate the output of 'useful' power.

#### Teaching notes

1 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.

2 This experiment could be set as a class activity if a suitable site is available.

This experiment was safety-checked in January 2006