Energy, work and power — practice question

A straight hill $AB$ is $400\,\text{m}$ long, with $A$ at the summit and $B$ at the foot, and it makes an angle of $4^\circ$ to the horizontal. A straight level road $BC$ is $750\,\text{m}$ long. A car of mass $1250\,\text{kg}$ has speed $5\,\text{m s}^{-1}$ at $A$ as it begins to travel downhill. During the descent, the resistive force on the car is $2000\,\text{N}$ and the driving force remains constant. The car’s speed on arriving at $B$ is $8\,\text{m s}^{-1}$. At $B$ the car continues along road $BC$. The driving force stays constant and is twice its value on the hill. The resistive force on the car remains $2000\,\text{N$}.