The kinetic energy of gas molecules is directly proportional to changes in temperature. When temperature increases, the kinetic energy of the gas molecules also increases; conversely, when the temperature decreases, the gas molecules' kinetic energy also decreases.

As the temperature of a system increases, the molecules within it begin to move faster, and the velocity of the particles is directly proportional to the kinetic energy. This concept is illustrated through the equation KE = (1/2)mv^2, where KE is the kinetic energy, m is the mass and v is the velocity. In such calculations, the temperature is measured in degrees Kelvin.

When the temperature of a gas increases but the pressure remains the same, the volume of the gas increases, meaning that the molecules must cover a greater amount of space in the same amount of time by moving faster. The kinetic energy increases as collisions between the different molecules increase and the velocity of the movement increases. This behavior is demonstrated by Charles' Law, with the equation V/T = k. In this equation, V is volume and T is temperature, and the two are directly proportional. Similarly, the temperature and the pressure are also directly related, as in the Pressure Law equation, P/T = k, where P is pressure and T is temperature.