Question

When an apple falls freely from the tree towards the ground, then its total mechanical energy _________.

• A. increases
• B. decreases
• C. first increases and then decreases
• D. remains constant

Answer 1

The correct option is D

remains constant

According to the law of conservation of energy, the total energy of a system will always remain constant. This is true in a free fall. When the apple is at rest at the highest point, the only form of mechanical energy it has is potential energy. Once the apple starts falling, the amount of P.E. it contains decreases and K.E. increases by the same amount simultaneously, thereby keeping the total energy constant.