Mathematics 9709 · AS & A Level · Energy, work and power

Energy, work and power — practice question

A resistive force of magnitude $1350\,\text{N}$ acts continuously on a car with mass $1200\,\text{kg}$.
(i)[2]

The car is travelling along a straight, level road at a constant speed of $32\,\text{m s}^{-1}$. Find, in $\text{kW}$, the rate at which the engine of the car is working.

(ii)[3]

The car moves at a constant speed up a hill inclined at an angle of $\theta$ to the horizontal, where $\sin\theta = 0.1$, while the engine is working at $76.5\,\text{kW}$. Find the speed.

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