Mathematics 9709 · AS & A Level · Energy, work and power

Energy, work and power — practice question

The combined mass of the cyclist and the cycle is $80\,\text{kg}$. There is no resistance to motion.
(i)[2]

A cyclist travels along a horizontal straight road at a steady power output of $P\,\text{W}$. Determine $P$ if the cyclist’s speed is $5\,\text{m s}^{-1}$ when the acceleration is $1.2\,\text{m s}^{-2}$.

(ii)[3]

The cyclist is travelling up a straight hill at an angle $\alpha$, where $\sin \alpha = 0.035$. Determine the cyclist’s acceleration at an instant when he is producing $450\,\text{W}$ and has speed $3.6\,\text{m s}^{-1}$.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: Apply $DF = \frac{P}{v}$ together with Newton’s second law

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