Pressure
Section: Physics | Syllabus: Cambridge IGCSE Combined Science (0653)
Pressure
- pressure is defined as the force acting per unit area
- Formula:
- p = (F/A)
- Where:
- p = pressure (Pa)
- F = force (N)
- A = area (m²)
- 1 pascal (Pa) = 1 newton per square metre, so 1 Pa = 1 N/m^2
Pressure, force and area formula triangle
Pressure, Force and Area
- for a given force, a smaller area produces a larger pressure, and a larger area produces a smaller pressure
- spreading a force over a large area lowers the pressure; concentrating a force onto a small area raises the pressure
- everyday examples:
- tractors have large tyres, which spread their weight over a large area to lower the pressure on the ground and stop them sinking into soft mud
- drawing pins have a sharp point with a very small area, which concentrates the force to create a large pressure that pushes the pin into a wall
- a stiletto heel has a small area, creating a large pressure that can sink into soft ground, while a flat shoe spreads the same weight over a larger area, creating a much lower pressure
The same force produces a much higher pressure when it acts over a smaller area
Worked ExampleQuestion: Museli's box weighs 240 N and rests on a base of area 0.4 m². Calculate the pressure it exerts on the floor.
Museli's box: weight 240 N, base area 0.4 m²
Answerp = (F/A) = (240/0.4) = 600 Pa
Interactive revision notes, videos and practice questions load below.