Physics 5054 · O Level · Pressure

Pressure — practice question

A horizontal solid rectangular concrete block is resting on level ground, with one of its largest faces touching the ground. Fig. 3.1 gives the block’s dimensions. The block has a weight of 240 N.
(a)[2]

Calculate the pressure exerted on the ground by the block.

(b)[1]

State why the total pressure on the ground below the block is greater than the result in (a).

(c(i))[1]

Since the block has uniform density, State the height above the ground of the block’s centre of mass.

(c(ii))[2]

The block is turned about its lower, left-hand edge until it comes to rest on one of its smallest sides, as shown in Fig. 3.2. Explain why work is done while the block is being rotated.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: Using $P = F / A$: $240 / (0.44 \times 0.21) = 240 / 0.0924$.

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