Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A cyclist is moving on a straight, level road. The combined mass of the cyclist and her bicycle is $80\,\text{kg}$. A constant resistive force of magnitude $32\,\text{N}$ opposes the cyclist’s motion. At a moment when she is moving at $7\,\text{m s}^{-1}$, her acceleration is $0.1\,\text{m s}^{-2}$.
(a)[3]
Calculate the cyclist’s power output.
(b)[2]
Calculate the steady speed the cyclist can keep if both her power output and the resistance force stay the same.
(c)[6]
Given that the cyclist’s speed at the top of the hill is $7.5\,\text{m s}^{-1}$, calculate her speed at the bottom of the hill.
Worked solution & mark scheme
This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Use the driving force relation $DF=\tfrac{P}{7}$” …