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

Energy, work and power — practice question

A car with mass $1100\,\text{kg}$ is travelling along a road while a steady resisting force of $1550\,\text{N}$ acts opposite to the motion.
(i(a))[2]

The car travels in a straight line along a horizontal road at a steady speed of $40\,\text{m s}^{-1}$. Calculate, in $\text{kW}$, the power output of the car engine.

(i(b))[3]

If this power is then reduced suddenly by $22\,\text{kW}$, find the instantaneous deceleration of the car.

(ii)[3]

The car is now moving at a constant speed up a straight road that is inclined at $8^\circ$ to the horizontal, with the engine operating at $80\,\text{kW}$. If the resistance force is unchanged, find this constant speed.

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