Answer :
As per work energy theorem,
Work done by all forces = change in kinetic energy
If kinetic energy is different than your work input, then certainly other forces which are responsible for this discrepancy. These forces can be internal or external.
Work done by all forces = change in kinetic energy
If kinetic energy is different than your work input, then certainly other forces which are responsible for this discrepancy. These forces can be internal or external.