Molecular Kinetic Theory

Brownian motion

• Smoke particles are bombarded by the air
• at any given instant, there are more collisions on one side of the particle than the other
• therefore the change in momentum on each side is unequal
• therefore a force F results.

Ideal gas equation

pV=nRT

p = k/V (at a constant temperature)

When volume V decreases:

• molecules travel less distance before they collide with the container
  • therefore there are more collisions every second with the container
  • therefore rate of change of momentum increases
  • therefore pressure increases.

p = kT (at a constant volume)

When temperature T increases:

• molecules have a greater velocity
  • therefore there are more collisions every second with the container
  • therefore rate of change of momentum increases
  • therefore pressure increases.

pV=(1/3)Nm<c²>

Where

• N = the number of molecules
• m = the mass of each molecule (kg)
• <c²> = the mean square speed

Zeroth law

When you place two bodies in contact and there is no net energy transfer between them:

• they are in thermal equilibrium
• therefore they have the same temperatures.

When two bodies are in contact, they will remain in comtact untill they are sepreted by an external force. That mean force can not be tranfered into bodies in contact untill work is done.