energy cannot be created or destroyed, but only transferred from one store to another
energy density
the amount of energy in a fuel per unit volume
unit of energy density
J m–3
Mechanical energy
the sum of kinetic energy, gravitational potential energy and elastic potential energy within a system. In the absence of resistive forces, mechanical energy is always conserved
Power
the rate of work done or the rate of energy transfer. It is measured in watts (W)
Scalars
quantities that are fully described by just a magnitude
vectors
quantities that are fully described by a magnitude and a direction
uniform acceleration
velocity changes at a constant rate
Ideal gas
a good approximation of a real gas when it is at low pressure, low density and high temperature
inelastic
a collision in which there is a loss of kinetic energy
elastic
a collision in which there is no loss of kinetic energy
Tempereture
a measure of the average kinetic energy of the particles in a gas
