Question

The work done by the external forces on a system equals the change in …..

Answer 1

1. If the work done on the object is by the external force, there is a change in the total mechanical energy of the system, that is, the sum of kinetic energy and potential energy.
2. If the work done is positive, it means the object gains some energy and if it is negative, then the object loses some energy.

Therefore, the work done by the external forces on a system equals the change in Mechanical Energy.