Question

what will cause greater change in kinetic energy of a body ? changing its or changing its velocity . explain

Answer 1

Kinetic energy = 1/2 mv2

Rate of change of kinetic energy keeping mass constant
KE = kv
Its a linear relation

On the other hand, if we keep velocity constant and increase mass
KE = k
It will remain constant

Hence, change in velocity will cause a greater change in Kinetic energy

Answer 2

Kinetic energy is directly proportional mass as well as velocity. But, you must note the fact that kinetic energy is directly proportional to the square of velocity. Therefore, changing the velocity will cause a greater change in kinetic energy.