I was watching a tennis tournament today, and the commentator said he thought Sampras' second serve was much better than Rodick's. One of the factors he cited was that Pete's serve produced a heavier ball, since he used a much heavier racket. This sounds a bit strange to me. Given the same spin and trajectory isn't one tennis ball moving at 120 mph the same as another, regardless of the weight of the racket used to produce the 120 mph serve?
If the speeds of the two serves and the spin of the ball
(direction as well as rate of spin) are the same then the two serves will have the same
"power".
The momenta of the two balls will be the same and so will be just as
difficult to stop or return. The ball will seem equally "heavy".
However if the server
moves their racket at a given speed then a heavier racket will give the ball a greater
speed.