Form 2 Chapter 6: AIR PRESSURE

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6.1 Air Pressure

6.1.1 Kinetic Theory of Gases

The kinetic theory of gases states that

Air or gases are matters that have particles that move randomly in all

directions.

Gas particles in a container collide with each other and with the walls

of the container all the time.

Gas particles exert a force on the wall of the container

This force produces a pressure

Air presses down on all things in the Earth's surface. The pressure exerted

by air particles on the surface on an object is known as air pressure or

atmospheric pressure.

The features of air pressure are :

Acts in all direction

Changes from one place to another

Decreases the higher we go above ground level. This is due to at high

place, the amount on air decreases. This explains why the air pressure

on the top of a mountain is lower that at the foot of the mountain.

Form 2 Chapter 6: AIR PRESSURE

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6.1.2 Factors Affecting Air Pressure

Air pressure is affected by volume and temperature of air.

Factor Effect Explanation

Volume Air pressure increases with decreasing volume of the container and produces a larger force.

As the volume decreases, the air particles move in a smaller space. As a result, more particles hit the wall of the container. Therefore, a higher pressure acts on the wall of the container.

Temperature Air pressure increases as the gas increases.

As the temperature increases, the air particles have more kinetic energy. More particles hit the wall of the container with greater force. Therefore, the pressure increases.