Originally Posted by sureshs
Then you are saying the velocity is constant almost at collision, even if the racket was accelerating before? Then toly's point would be that the person applies no force, and of course he doesn't, because we just made the acceleration 0. That would be true for anything! If we say we will go by a boxer's hand's final speed only, we can claim that the boxer did not do anything at the instant of impact!
What use is that?
The racquet could be accelerating all the way to impact. But the actual impact lasts only a few milliseconds. As toly pointed out, how much energy could the force have contributed in that time? IMO, negligible for the purposes of this calculation. If someone can prove this to be wrong, I will accept it - I don't have any means other than the above logic to prove my assertion.