When is the greatest fraction of kinetic energy transferred?

Question by : PHYSICS :|||||||||||||||||||||||||?
When a particle suffers a head-on elastic collision with another particle, initially at rest, the
greatest fraction of kinetic energy is transferred if

A. the incident particle is initially traveling very fast
B. the incident particle is traveling very slowly
C. the incident particle is much more massive than the target particle
D. the incident particle is much less massive than the target particle
E. the incident and target particle have the same mass

the answer is E
but why?
thank you
Answers and Views:

Answer by Kalpana
In elastic collision, both kinetic energy and momentum are conserved. In an elastic collision between two bodies of equal masses, the velocities get exchanged. In our case since the second body initially was at rest, after collision, the first body comes to rest transferring 100% of its kinetic energy to the second body!