Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A car with mass $1400\,\text{kg}$ is travelling on a straight horizontal road and experiences a resistance of magnitude $350\,\text{N}$.
(a)[2]
Determine, in $\text{kW}$, the rate at which the car’s engine is doing work when it is moving at a constant speed of $20\,\text{m s}^{-1}$.
(b)[3]
Determine the acceleration of the car when its speed is $20\,\text{m s}^{-1}$ and the engine is working at $15\,\text{kW}$.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply the power formula $P = Fv$, for example $P = 350 \times 20$” …