Question

During Cooling , the kinetic energy of the molecules falls. Why does this happen?

Answer 1

Because what we call 'cooling' is our big-world perception of the result when the kinetic energy of the molecules in a substance decreases. Reduced gas pressure is another one.

Answer 2

because when you cool something down, heat energy is being released, so kinetic energy of these molecules decreases because they have less energy stored in them