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

Energy, work and power — practice question

A car with mass $1200\text{ kg}$ is moving along a level road.
(i(a))[2]

A constant resistance to motion is stated. The car’s engine is operating at $16\text{ kW}$ while the car moves at a steady speed of $40\text{ m s}^{-1}$. Determine the resistance to motion.

(i(b))[3]

The power is then raised to $22.5\text{ kW}$. Determine the car’s acceleration at the moment it is moving at $45\text{ m s}^{-1}$.

(ii)[3]

It is now stated that the resistance to motion of the car is $(590 + 2v)\text{ N}$ when the car’s speed is $v\text{ m s}^{-1}$. The car moves at a constant speed while the engine works at $16\text{ kW}$. Find this speed.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Applies power equation $16000=F\times40$

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