How are professional tennis players able to return super-fast serves? Originally answered on July 11, 2016.
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Answer by Taylor Breland:
What if I told you players aren't actually returning a 147 mph serve? What if I told you that every serve you actually hit or see a pro hit is a lie? OK, maybe not a lie, but it's deceiving nonetheless.
When you serve a tennis ball, you have many things acting against you that decrease the speed of the ball from the time you make contact to the time it reaches your opponent. In fact, the speed of a serve (the number you see on the screen) is a measurement of the velocity taken directly after the racquet makes contact with the ball, not when the ball makes contact with the ground on the opposite side. The forces that work against your serve include gravity (obviously), air resistance, and friction, just to name a few. We know this from Newton's first law. The ball loses velocity over that small amount of time it is in the air, then once it makes contact with the ground, then once it bounces up in your direction.
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I don't have the exact numbers, but it is estimated that a ball loses almost 50 percent of its velocity by the time it reaches your racquet on the other side. So a 147 mph serve is really something like 73 mph. These numbers change dramatically depending on the surface and the conditions put in place on the ball.
Aside from all of these conditions that slow a ball down, it still doesn't take away from the fact that the ball has a limited distance to travel to get from the server to the opponent on the other side — 78 feet, to be exact (from baseline to baseline). This means that your reaction time must be very good, independent of the speed behind the ball. It takes a lot of training and technique to put the racquet in contact with the ball. You'll notice that a lot of players will stand far behind the baseline to give the ball an extra decrease in velocity so they get that much more time to hit the ball. Rafael Nadal is a prime example.
I've been taught, as most players are, that you don't have the time to set up a full backhand or forehand. You have to anticipate the direction of the ball and pretty much block it back and use the pace to your advantage. It's very hard against a big server, but the more practice, the better.
Hope that helps. As a side note, I recommend you look up how baseball players are able to hit major league fastballs. The timing and anticipation you need are insanely ridiculous.