PRESSURE

Pressure is defined as force per unite area.

1. Surface has an inversely proportional relationship with Pressure.

2. The amount of Force has a directly proportional relationship with Pressure.                       

 

Formula: pressure = Force/Area

                  P=F(N)/A2

Pressure is measured in Pascal’s (Pa)

 

1 Pa = 1N/m2  

I bar = 100 kPa

1 atmospheric pressure = 101,3 kPa

 

Atmospheric pressure is the amount of pressure that the molecules in the air exert on an object at sea level.

Question.

Determine the amount of pressure exerted by a brick if it has a mass of 2.5Kg and an area of 10cm2.

Answer:  P= F/A

                 P= 2.5/10

                 P= 0.25 Pa

 

Conversions:

1m = 1000mm

1m = 100cm

1m = 10dm

1mm = 1/1000m = 10-3m

1cm = 1/100m = 10-2m

1dm = 1/10m = 10-1m

 

Convert the following to m2

1cm2

Answer:  1cm2  = (1cm)2 = (10-2)2 = 10-4 m2

 

Pascal’s law: if pressure is applied to a liquid that is confined, the liquid will then transmit that same amount of pressure in all directions at the same rate.

 

MA = mechanical advantage.

Mechanical advantage is when a small input force is used to create a large output force.

 

F1/A1 = F2/A2

1/2 = 5/10

 

When a force of 1kg is added to surface A the piston transmits the same amount of pressure in all directions at the same rate. This allows the piston to lift an object of 5kg on the other side because the surface B was increased.

The piston used 1kg of pressure and transmitted it into 5kg of pressure that is Mechanical Advantage.

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