When the body falls freely towards earth, the potential energy of the body decreases while the kinetic energy of the body increases, but the total energy remains constant at all points during the motion. This is due to the conservation of mechanical energy. As the body falls towards the Earth, its potential energy decreases because it is moving closer to the ground, while its kinetic energy increases because it is gaining speed. The total energy of the system (kinetic energy plus potential energy) remains constant.