PRESSURE

These facts are examples of the effects of PRESSURE between two surfaces. We can study these effects by the following investigations.


These simple experiments should have shown you that:

THEORY

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 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).

Examples of HIGH PRESSURE

the point of a drawing pin, stiletto heels, running spikes, chair legs and the ground, a nail point, stilts, thin rucksack straps, cheese wire
(these are concentrated forces)

Examples of LOW PRESSURE

skis, caterpillar tracks, snow shoes, head of a drawing pin, large tyres and the ground, wide rucksack straps
(these are "spread out" forces)