If by what you mean is are you allowed to hit the return before it bounces - NO.
You can only be awarded an ace when you serve the ball.
No, only the person standing diagonal from the server at the baseline may return
In tennis when the opposing player is unable to return the first serve, this is known as an ace. An ace is also a hole in one in golf, and obviously card games.
You have to let the ball bounce in the service box before returning the serve.
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
There are two types of serve that a player cannot return, one is an Ace and one is just called Unreturnable. An Ace is when the returner cannot get their racket to the ball at all. An Unreturnable is when the returner touches the ball, but cannot return it within the court.
Returning a 120+ mph serve is by far harder because there is a bigger area where they can serve were as baseball players barley have to move their feet because of a strike zone. Also there is a smaller distance between the ball and raquet. Tennis players have to be on their toes constantly and needs a lot of strength to return serves.
Almost all of your joints are used in tennis, but the main ones in a tennis serve are the knee joints, and elbow joints.
You can hit an underhand serve in tennis; however, the overhand serve is more effective because it is more powerful. That is why you don't see the underhand serve used much.
a serve
A tennis ball!