Pressure

Pressure is how spread out a force is. The same force on a smaller area gives a bigger pressure, which is why knives are sharp and snowshoes are wide.

Key facts

  • Pressure = force ÷ area: P = F/A.
  • Units: N/m² (also called pascals, Pa), or N/cm².
  • Smaller area → bigger pressure.
  • Pressure in a liquid increases with depth.

Worked examples

Example 1

A 600 N box rests on an area of 2 m². What pressure does it put on the floor?

  1. Divide the force by the area. P = 600 ÷ 2
  2. So P = 300 Pa

Answer: 300 Pa

Example 2

A 60 N force pushes a drawing pin with a point of area 0.5 mm². What is the pressure in N/mm²?

  1. Force divided by the tiny area. P = 60 ÷ 0.5
  2. So P = 120 N/mm²

Answer: 120 N/mm²