Pressure is the force per unit area.

This means that the pressure a solid object exerts on another solid surface is its weight in newtons divided by its area in square metres.

In this short version of the equation,

• F represents force which is measured in newtons
• a represents area which is measured in m²
• p represents pressure which is measured in pascals
• 1 pascal = 1 N/m²

Area is calculated by this equation.

A metre is an unit of length and width.

To increase pressure, increase the force or reduce the area the force acts on. To cut up your dinner you can either press harder on your knife or use a sharper one (sharper knives have less surface area on the cutting edge of the blade).

To reduce pressure, decrease the force or increase the area the force acts on. If you were standing on a frozen lake and the ice started to crack, you could lie down to increase the area in contact with the ice. The same force (your weight) would apply, spread over a larger area, so the pressure would reduce. Snowshoes work in the same way.