Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A car with mass $1000\,\text{kg}$ moves in a straight line on a level road while experiencing total resistive forces of $300\,\text{N}$.
(i)[3]
Find, in $\text{kW}$, how quickly the engine is doing work when the car moves with constant speed of $40\,\text{m s}^{-1}$.
(ii)[3]
Find the acceleration of the car when it is moving at $25\,\text{m s}^{-1}$ and the engine power is $90\%$ of the value obtained in part (i).
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Because driving force equals resistance: $DF = 300$” …