Physics Definitions A level

Specific Heat Capacity

The energy required per unit mass to change the temperature by 1 Kelvin

Specific Latent Heat

The energy required to change the phase per unit mass while at constant temperature

Specific Latent Heat of Fusion

The energy required to change unit mass of a substance from solid to liquid while at a constant temperature

Specific Latent Heat of Vaporisation

The energy required to change the unit mass of a substance from liquid to gas while at a constant temperature

Root mean squared speed

The square root of the average squared speed of particles in an ideal gas.

Pressure

The force exerted per unit cross sectional area, measured in pascals

Kinetic theory of gases

1) Large number of molecules in random rapid motion

2) Particles occupy negligible volume compared to gas volume

3) Collisions are perfectly elastic and time is negligible between and during.

4) Negligible forces between particles except during collisions.

Thermal Equilibrium

A state in which there is no net flow of thermal energy between the objects involved, that is, objects in thermal equilibrium must be the same temperature.

Absolute Zero

The lowest possible temperature, the temperature at which substances have minimum internal energy.

Internal Energy

The sum of randomly distributed kinetic and potential energies of the atoms, ions or molecules within the substance.

Brownian Motion

The continuous random motion of small particles suspended in a fluid, visible under a microscope.

Boyle’s Law

The pressure of an ideal gas is inversely proportional to its volume, provided that the mass of gas and the temperature do not vary.

Charles’ Law

A gases expand at the same rate when heated. The volume of a fixed mass of gas is proportional to its temperature when kept at constant pressure.

Pressure Law

The pressure of a fixed mass of gas is proportional to its temperature when kept at a constant temperature.

Ideal Gas

A model of a gas including assumptions that simplify the behaviour of real gases.