How do you calculate pressure?

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Pressure is the force exerted by one object on another object over a given area of contact. 

The following equation can help understand and also explain how pressure works: 

pressure = force / area  

p = f / a

If you imagine 'f' as being above 'a' in the equation then it should help you remember that Pressure is the Force OVER the Area given.

an example of this is:

If a 5 Newton force is applied to an area of 2m2, what is the Pressure?

f = 5 Newton , a = 2m

Therefore,  p = 5 / 2 = 2.5 N/m

You may of seen Pressure written in Pascals (Pa), this is fine as N/mand Pa are directly proportional. 

eg. 1N/m= 1 Pa 

It is also worth understand how changing the Force and Area affects Pressure.

To increase pressure - increase the force being applied or reduce the area the force is acting on.

E.g. When pushing a pin into a cork board you must press harder (apply more force) to make it pierce the surface. If the pin has a sharp pointed tip then the area that is touching the cork is small meaning pressure at that point is very large. 

To decrease pressure - decrease the force being applied or increase the area that the force is being applied too. 

E.g. if your were to lightly press the pin into the cork board it would likely not pierce the surface and pin into the board. The reason for this is there is not enough force being applied by your hand to push the pin into the cork. Also if the tip of the pin was blunt and rounded rather than sharp and pointed the increase in area means the force you are applying is spread over a greater area. Therefore the pressure being exerted by the pin is smaller.

 

Summary

Pressure = Force / Area 

p= f / a

1N/m2 is the same as 1 Pa 

Increase pressure - increase the force or reduce the area.

Decrease pressure - decrease the force or increase the area.

Marc H. GCSE Science tutor, GCSE ICT tutor, GCSE Design & Technology ...

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