It's measured because the first serve speed is a very important statistic. The faster a serve is, the harder it is for the opposing player to return. By knowing a person average first serve speed, you can then decide on what kind of strategy you can use to return the serve and win the point
It depends on how hard you want to hit the ball
Average Top Spin Ground stroke speed is 62 MPH on the pro tour, and average Slice speed is 46 MPH. some ground strokes have reached above 105 MPH, But on average rally speed is 62 MPH Tennis Professional J R A
After careful deliberation upon this topic, I have discovered that my results are unanamous. The average speed of a tennis balls machine ranks in at a whopping 80 miles per hour.
96 km/h 60 m/h
In tennis, the average speed of a serve for a man can range from from 70mph up to the world record of 163.7 mph. A pro would average in the high end, 120-130mph.As of March 2014, the fastest professional serve speed for a man is held by Samuel Groth at 163.7mph (263.4 km/h). This was set at the 2012 Busan Open Challenger Tennis.Additionally, other top speed servers include:Milos RaonicAkbano OlivettiIvo KarlovicJerzy JanowiczJohn IsnerAndy RoddickTaylor DentBenjamin BeckerHeight does seem to play a factor in how fast a player can serve the ball.
UPDATE: Andy Roddick's record was broken on March 5, 2011 by Croation Ivo Karlovic during a doubles match in the first round of the Davis Cup. The new record is 156 mph (251.06 kph). The fastest serve ever recorded was 155mph by Andy Roddick in 2004
The ball loses 50% of its speed by the time it reaches the net.
The fastest ever serve recorded; 251 Km/h, was by Ivo Karlovic.
Jai-alai
Andy Roddick 153 mph June 11 2004
The fastest recorded speed for a ball in competition is 131 mph (211 km/h) from a tennis serve hit by Samuel Groth in 2012.