Work Energy And Power

The correct answer is option (C) : 3m
In elastic collision kinetic energy and momentum are conserved.
Let be the initial velocity of a particle before the collision and
the final velocity after collision, then change in kinetic energy is given by



Also from the conservation of momentum, we have

From given information where a is acceleration, is displacement and is a proportionality constant. Let for any displacement from 0 to the velocity changes from to v. [ is loss in KE]

As, mechanical energy Kinetic energy, using or