A car travels along a straight, level road at a constant speed of $36\,\text{m s}^{-1}$ and experiences a constant resistive force of $850\,\text{N}$. Find, in $\text{kW}$, the rate at which the car’s engine is working.
The car moves at a constant speed up a hill and has the same resistance as in part (i). The hill is inclined at an angle of $\theta^\circ$ to the horizontal, where $\sin \theta = 0.1$, and the engine is working at $63\,\text{kW}$. Find the speed of the car.
The car goes down the same hill while the car engine works at a steady rate of $20\text{ kW}$. The resistance is not constant. The car starts at $20\text{ m s}^{-1}$. Eight seconds later it is moving at $24\text{ m s}^{-1}$ and has travelled $176\text{ m}$ down the hill. Use an energy method to find the total work done against the resistance during the eight seconds.