Thursday, June 30, 2011

Physics Form 4: Chapter 3 - Gas Pressure

Gas pressure in a closed container is caused by the frequency of collision between the gas molecules and the walls of the container. All collisions are elastic.

A molecule with a mass, m moving with a velocity  v, has a momentum = mv

After colliding with the wall elastically, the  momentum with it bounces back is   –mv.

Change in momentum = mv – (-mv) = 2 mv. Thus, produce an impulsive force. The force acting on an area of the wall produces pressure in the container.

 Gas pressure can be increased by:
  • increasing the temperature of the gas
  • reducing the volume of the gas.
  • increasing the number of gas particles.
 Gas pressure can be measured by using manometer as shown below:

Click on the diagram below to play!

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