Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A car with mass $1600$ kg is travelling on a straight horizontal road at constant power $14$ kW. It takes $25$ s to go from point $A$ to point $B$ on the road.
(i)[2]
Calculate the work done by the car’s engine as the car moves from $A$ to $B$.
(ii)[5]
The resistance opposing the car’s motion is constant at $235$ N. The car’s accelerations at $A$ and $B$ are $0.5$ m s$^{-2}$ and $0.25$ m s$^{-2}$ respectively. Find the increase in kinetic energy as the car moves from $A$ to $B$.
(iii)[3]
Calculate the distance $AB$.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply $P = \frac{WD}{\Delta t}$ together with $WD = 14000 \times 25$” …