friction decreses
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The higher the temperature is, the lower the coefficient of friction is. Temperature is the measure of the molecular kinetic motion of a substance. And, if the temperature increases, the molecular movement (vibrations) increase allowing the substance to have less friction. Consider something like motor oil, which has different viscosities at different temperatures. When it's hot, the viscosity decreases (it gets thinner). And, when it's cold, the viscosity increases (it gets thicker). This is due to the internal friction between the molecules being lower at high temperatures and higher at low temperatures.