Physics 5054 · O Level · Work

Work — practice question

A lorry with mass $4.4 \times 10^{4}\,\text{kg}$ is moving along a straight, horizontal road at $20\,\text{m s}^{-1}$.
(a)[3]

Calculate the kinetic energy of the lorry.

(b(i))[1]

The lorry driver spots an obstruction ahead and applies the brakes. The lorry slows down and comes to a stop. It stops 40 m from the point where the driver first applies the brakes. As it slows, the lorry's kinetic energy falls to zero. The decrease in kinetic energy is caused by work being done by the braking force on the lorry. State the formula that links the work done to the braking force.

(b(ii))[2]

Calculate the braking force acting on the lorry.

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