Ncert Exercises & Solutions

A body is falling freely under the action of gravity alone in a vacuum. Which of the following quantities remain constant during the fall?
1. kinetic energy
2. potential energy
3. total mechanical energy
4. total linear momentum

As the body is falling freely under gravity, the potential energy decreases, and kinetic energy increases but total mechanical energy (PE + KE) of the body and earth system will be constant as an external force on the system is zero.