Studying mathematics I've learned to never assume. That's the only reason I'm being picky about what play means.
I suggest you study physics too, then you could formulate your own proof about how fast you would need to swing the racquet to generate the required wind to reverse the path of a tennis ball and blow it back over the net. On the plus side, having done so you'd realise you must have another super power to go with the telekinesis.