Pressure

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Description

This is a basic physics GCSE tutorial exploring what pressure is in physics. Video tutorial to come.

What is pressure?

Pressure is not a force per se. It is a way of describing how much force is being applied to a given area at any one time i.e. it describes the intensity of the force.

Pressure = force ÷ perpendicular area

or

P = F ÷ A

Where

Take this shoe box for example. It has a weight of 80 N. The box is exerting this force on an area of 2 squared metres of the ground (Hint: hover over the image below to see how area is calculated).



The pressure experienced from this interaction is 40 pascals.
P = F ÷ A
P = 80 N ÷ 2 m2
P = 40 Pa


Why is pressure relevant?

The force being applied on a surface can be the same, however the difference in area upon which it is applied can influence what happens. For example the shoe box in the above example does not cause any damage. If the area was greatly reduced (as in the example below), the pressure exerted by the same force would be significantly greater.

The resultant pressure from a force of 80 N exerted on the area of a pin prick (0.00000025 m2) would be 320,000,000 pascals (as calculated below).

P = F ÷ A
P = 80 N ÷ 0.00000025 m2
P = 320,000,000 Pa

This significant increase in pressure is what allows a person to stick a pin into most surfaces with relative ease.

Pressure can also be exerted by fluids, as you'll discover if you're doing higher-level GCSE physics. Those tutorials are still to come.