When the temperature of a substance is lowered, its particles move slower and have less kinetic energy.

Here's why:

* Temperature is a measure of the average kinetic energy of the particles in a substance. Kinetic energy is the energy of motion.

* Lowering the temperature means reducing the average kinetic energy of the particles.

* As the particles move slower, they collide less frequently and with less force. This leads to a decrease in the overall energy of the substance.

This is why substances often change states when their temperature is lowered. For example, water freezes into ice because the water molecules slow down and become more tightly packed together.