Question

An object of mass, m is moving with a constant velocity, v. How much work should be done on the object in order to bring the object to rest?

Answer 1

The object is in motion, so its energy = kinetic energy = 1 /2 mv² 

The kinetic energy of the object, when it comes to rest = 0. 

Work done on object = change in kinetic energy 

                                  = 1 /2 mv² – 0 

                                  = 1 /2 mv²