Kinetic energy, temperature and the Kelvin scale
Imagine a gas is trapped inside a container which has a fixed size (its volume cannot change). Gas pressure is caused by the collisions of the gas particles with the inside of the container as they collide with and exert a force on the container walls. Then the gas is heated up.
As the temperature of the gas increases, the particles gain kinetic energy and their speedThe distance travelled in a fixed time period, usually one second. increases. This means that the particles hit off the sides more often and with greater force. Both of these factors cause the pressure of the gas to increase.
A temperature of absolute zero is the point at which the gas particles stop moving. This corresponds to a temperature of \(-273^{\circ}C \). Particles have no kinetic energy at all so no energy can be removed and the temperature cannot get any lower. With no kinetic energy and now stationary, the particles will exert no pressureForce exerted over an area. The greater the pressure, the greater the force exerted over the same area. either.
Using this idea of absolute zeroA temperature where the kinetic energy of a particle is zero, eg absolute zero has a temperature of 0 K., it makes sense to create a new temperature scale 鈥 one where 'zero' is 'absolute zero'.