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Work done by the cyclist causes the bike to accelerate, and the energy is transferred to the kinetic energy of the bike. An equation is given to calculate the kinetic energy of an object with known mass and speed. Even when a cyclist is not accelerating, work is still being done. In this case, the work done is transferred to heat due to frictional forces.
This clip is from:
First broadcast:
20 March 2008

Classroom Ideas

The clip can be used in a lesson giving an overview of forces. Students could watch the clip then describe and explain situations in which attempts are made to increase or decrease the force of friction. For the example of cyclists or other vehicles, consider the energy transfers that take place, the energy that is wasted and how this can be reduced. Options should include aerodynamics, lubrication of moving parts and changing wheels or tyres to reduce surface area.

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