Pressure

• Pressure describes how concentrated a force is. It is measured in Pascals (Pa) or Newtons per Square Metre (N/m²).

• Rule for Pressure

Pressure (Pa) =	Force (N)
	Contact Area (m2)

• Example of Pressure Rule
  
  Q. What pressure is exerted by a boy with a force of 400 newtons on a surface that has an area of 2 square metres?

A.	Pressure =	Force	=	400 N	= 200 Pa
		Contact Area		2 m2

• Examples of Pressure

1. A karate chop using the side of the hand with the same force as a flat-handed punch would have greater pressure.
2. The drivers of four-wheel drive vehicles stuck in a sand trap let some air out of their tyres so that there is a greater contact area between the tyres and the sand, reducing the pressure and increasing friction.
3. The air pressure above the wing of an aircraft is less than that below the wing. This causes the aircraft to move upwards.