Originally Posted by wanda
I believe a heavy ball is one that has speed and spin.
You can hit a fast ball with little spin and it's easy to get back and control. If you're faced with a ball with spin and pace when it hits your racket it's much more difficult to control due to the spin, hence it feels heavy.
Last summer I played with this person and he hit absolutely flat ball almost with zero spin. And his ball was very fast and felt very very heavy. So probably spin is not a necessary condition for heavy ball (while speed is).