Pressure under a Solid

3 marks · Normal

A metal plate rests on soft ground. The plate has a weight of 600 N and covers an area of 0.75 m².

(a)

Calculate the pressure the plate exerts on the ground. Give your answer in Pa.

[2 marks]

(b)

Explain how the pressure would change if the area of the plate were halved, but the weight stayed the same.

[1 mark]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) 800 Pa

(b) The pressure would double. · must show Doubling of pressure, Inverse relationship explanation

Common mistakes: not halving the area; not explaining inverse relationship

Show mark scheme and worked solution

Marking points

M1 (a) · 1 mark · Substitute values into p = F/A. (follow-through)

A1 (a) · 1 mark · Obtain correct answer with unit. (follow-through)

B1 (b) · 1 mark · Correct explanation (pressure doubles when area is halved, with force constant).

Worked solution

a) p = F / A = 600 N / 0.75 m² = 800 Pa

b) If the area is halved but force is constant, pressure will double, because pressure and area are inversely proportional.