Which of the following statements is correct about a freely falling body?
1. Total energy is constant.
2. Potential energy changes into kinetic energy.
3. Potential energy decreases.
4. Kinetic energy increases.
All 1, 2, 3, and 4
According to the principle of conservation of energy, energy can neither be created nor can it be destroyed. It can be only changed from one form to another. When the body is at the highest point, its velocity is zero so the kinetic energy is zero. The only energy it has is potential energy. When the body starts falling, its velocity increases and its kinetic energy starts increasing. Since energy cannot be created, total energy has to be constant. Moreover, when the body starts falling, its height decreases and hence potential energy decreases. It can be shown that an increase in kinetic energy is equal to the decrease in potential energy.
Hence, all the above statements given in the question are correct.