3.1 UNDERSTANDING PRESSURE

•  Pressure is defined as force per unit area. therefore, the smaller the area, the higher the pressure.

• The SI units for pressure are Newtons per square metre (N/m²), now called Pasals (Pa) ( 1 N/m² = 1 Pa). 
• You can also use Newtons per square cm (N/cm²).

• The pressure between two solid surfaces depends on two things:

                (a) the force between the surfaces
                (b) the area of contact between the two surfaces.

• The greater the force or the smaller the area the greater the pressure.

• The pressure of a given force increases as the surface area decreases.

3.1 UNDERSTANDING PRESSURE : APPLICATION

APPLICATION INVOLVING HIGH PRESSURE

• Increasing the pressure by reducing the area

• A sharp knife has a very small surface area on its cutting edge so that high pressure can be exerted 

 

• The studs on a football boot have only a small area of contact with the ground. The pressure under the studs is high enough for them to sink into the ground, which gives extra grip. 

APPLICATION INVOLVING LOW PRESSURE

• Reducing the pressure by increasing the area

• Skis have a large area to reduce the pressure on the snow so that they do not sink in too far.

• A tractor moving on soft ground has wide tires to reduce the pressure on the ground so that they will not sink into the ground