Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A car with mass $1250\,\text{kg}$ moves from the foot to the top of a straight hill of length $400\,\text{m}$, which makes an angle $\alpha$ to the horizontal where $\sin\alpha = 0.125$. The resistive force acting on the car is $800\,\text{N}$. Determine the work done by the car’s engine in each case below.
(i)[4]
The car moves at constant speed.
(ii)[5]
The car begins at $6\,\text{m s}^{-1}$, the driving force on the car is $3$ times larger at the top of the hill than at the bottom, and the car’s power output is $5$ times larger at the top of the hill than at the bottom.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Increase in PE $= 1250 \times 10 \times 400 \times 0.125$” …