(a)[2]
A car travels along a level straight road at a steady speed of $24\,\text{m s}^{-1}$ and experiences a constant resistive force of $480\,\text{N}$. Determine, in $\text{kW}$, the rate of work done by the car's engine.
(b)[5]
The car then descends a hill with gradient angle $\theta$ to the horizontal, where $\sin\theta = 0.09$. The engine is delivering a constant $12\,\text{kW}$. At the top of the hill, the car's speed is $24\,\text{m s}^{-1}$. After ten seconds, it has covered $280\,\text{m}$ down the slope and is moving at $32\,\text{m s}^{-1}$. Since the resistance is not constant, use an energy method to determine the total work done against resistance in the ten seconds.