What is pressure?

  • Pressure is a measure of how much force is acting on an area.

  • Pressure depends on both the force and the area, and is found using the relationship: Pressure = Force ÷ Area

  • This means that a smaller area will create a greater pressure with the same force acting on it.

A ski instructor explains how the shape of skis affects the pressure they exert on the snow

What is pressure?

Pressure can be thought of as the concentration of a force on an area and can be calculated using the equation: Pressure = force ÷ area

Force is measured in Newtons (N). Area can be cm² or m² and so pressure is measured in N/cm² or N/m².

For example a person might weigh 400 N and stand on one foot which has an area of 80 cm² so the pressure this person puts on the ground is 400 ÷ 80 = 5 N/cm²

You can see the effects of this equation in action if you press a drawing pin into a cork board. The pin point end pierces the cork board and stays in place, you couldn't do that with the flat end.

This is because the same force is concentrated onto a smaller area at the pin end which creates enough pressure for the pin point to pierce the cork board.

How to change the pressure

Skiers increase the area in contact with the snow by using skis. Their body weight is no longer concentrated on their feet but is spread out over the area of the skis. The lower pressure of the skis means the skier glides on the snow rather than sinking into it. In comparison, the smaller area of the boot creates a greater pressure, and as a result a person just wearing boots would sink into the snow.

Pressure in action

Footballers need to get a good grip on the ground. They use boots with studs in them.

The studs have a small area to make the pressure large enough to dig into the surface. That way they have better grip and will not slip.

Pressure quiz

Test your knowledge with this quick quiz.

Where next?

Discover more about this topic from around Bitesize.

How to show the difference between force and pressure
How to explain forces
How to make a magnetic compass