Calculate the pressure of a boy weighing 40 kg on a surface of 50 cm2.

Given:

m = 40 kilograms – the weight of the boy;

g = 10 Newton / kilogram – acceleration of gravity (constant value near the earth’s surface);

s = 50 square centimeters – surface area.

It is required to determine P (Pascal) – the boy’s pressure on the surface.

We convert the units of measurement of area from square centimeters to square meters:

s = 50 cm2 = 50 * 10-4 = 0.005 square meters.

Let’s find the force of gravity acting on the boy:

F = m * g = 40 * 10 = 400 Newtons.

The pressure will be equal to:

P = F / s = 400 / 0.005 = 80,000 Pascal = 80 kPa.

Answer: the pressure is 80 kPa.