Originally Posted by Chas Tennis
Why do you think moving forward relatively slowly at maybe 10-15(?) feet per second, slow compared to the ball velocity, adds so much stick to your volley?
I believe it's a combination of things, but the basic answer is when the form is correct the ball sees not just the mass of the racquet and arm, but much of the bodies mass as well.
Think of it like getting hit by a cyclist at relatively high speed versus getting hit by a truck at low speed. The energy from a massive object even at slow speed is much higher.