Understanding Gas Pressure and Atmospheric Pressure

Existence of Gas Pressure.

1) According to the Kinetic Theory Of Gases, molecules in a gas are always moving randomly and constantly colliding with the wall of its container.
2) Collisions of gas molecules with the walls of the container occur frequently, resulting in a change of momentum which exerts a force on the wall of the container.


Existence of Atmospheric Pressure.

1) The atmosphere is the layer of mixture of gases such an nitrogen, oxygen and carbon dioxide that surrounds the Earth.
2) The weight of this mass of the atmosphere exerts pressure on the surface is called atmosphere pressure.

Understanding Pressure in Liquids

    

Liquids always find their own level.

1) The pressure at any point in a liquid is due to weight of liquid above that point.

2)This shows that a liquid always finds it's own level.

3)This confirms the fact that the pressure in a liquid.

    (a) Depends on vertical depth.

    (b) Is independent of the shape and cross-sectional area        of the containing vessel.

Pressure

Pressure is defined as the force acting per unit area.

Pressure = FORCE  

                    AREA

Do you know that the pressure that acts on a surface will greater if the area over which the force acts is very small ?

 

The pressure exerted by hing-heeled shoes.

The pressure exerted by flat shoes.

The high-heeled shoes will sinks deeper into soil than the flat shoes. This is because the smaller the area of the shoes, the greater the pressure of the shoes that exerting on the ground.

*credit - Longman_Essential_Physics Form 4