Pressure (OCR A Level Physics): Revision Note

Pressure

• Pressure tells us how concentrated a force is, it is defined as the force per unit area

• This equation shows:

  • If a force is spread over a large area it will result in a small pressure

  • If it is spread over a small area it will result in a large pressure

Different pressure is exerted for the same force on different areas 

• The units of pressure depend on the units of area:

  • If the area is measured in cm² (and the force in N), then the pressure will be in N/cm²

  • If the area is measured in m² (and the force in N), then the pressure will be in N/m²

• Pressure can also be measured in pascals, Pa where 1 Pa is the same as 1 N/m²

• Pressure, unlike force, is a scalar quantity

  • Therefore pressure does not have a specific direction