Unit

The unit of pressure is N/m2 or pascal, Pa.

1 N/m2 = 1 Pa

For smaller areas, the units N/cm2 and N/mm2 are also used for pressure.

Pressure is only in pascals, Pa, when the force is in N and the area is in m2.

A pressure of 50 Pa means that a force of 50 N acts over an area of 1 m2.

Question

Calculate the pressure exerted by a paving slab of weight 250 N if the area of contact with the ground is 1.25 m2.

p = \frac{\text{F}}{\text{A}}

F = 250 N

A = 1.25 m2

p = \frac{\text{250 N}}{\text{1.25 m}^{2}}

p = 200 Pa

The pressure exerted by the paving slab is 200 Pa.