The average kinetic energy of the particles of a substance is directly proportional to the temperature.
The relation can be given as
KE = 1.5 k T
where k = Boltzmann constant , T = temperature in kelvin
as the temperature of the substance increase, the particles of the substance gains heat and this gain in heat increases the speed of particles.
we know that kinetic energy is directly proportional to the speed and is given as
KE = (0.5) m v²
so as the speed of the particles increase with increase in temperature, the kinetic energy of the particles also increase.