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GCSE Questions: Energy Changes

Q5. The graphic shows a cyclist riding along a straight, level road at a constant speed.

Complete these sentences:

As the cyclist rides along the road, the _ _ _ _ _ _ _ energy store in the cyclist's body decreases. The speed of the cyclist is constant when the work done by the cyclist is _ _ _ _ _ _ _ the work done against air resistance.

[2 marks]

The graph below shows how the speed changes as the power output of the cyclist changes.

(a)

(i) Write down the equation that links power, time and work done.

[1 mark]

(ii) Calculate the work done by the cyclist when his power output is 200 W for 1800 seconds.

[3 marks]

(b) Calculate the percentage increase in speed of the cyclist when the power output changes from 200 W to 300 W.

[2 marks]

(c) The maximum speed this cyclist can travel on a level road is 14 m/s. How does cycling uphill affect the maximum speed of this cyclist? Explain your answer.

[3 marks]

[Total 11 marks]