# Projectile Motion of a Tennis Ball crossing over the net

1. Feb 1, 2010

1. The problem statement, all variables and given/known data

During a tennis match, a player serves the ball at 23.4 m/s, with the center of the ball leaving the racquet horizontally 2.31 m above the court surface. The net is 12.0 m away and 0.900 m high. When the ball reaches the net, (a) what is the distance between the center of the ball and the top of the net? (b) Suppose that, instead, the ball is served as before but now it leaves the racquet at 5.00° below the horizontal. When the ball reaches the net, what now is the distance between the center of the ball and the top of the net? Enter a positive number if the ball clears the net. If the ball does not clear the net, your answer should be a negative number.

2. Relevant equations

y-y0=vy0cosx+1/2at^2
x-x0=vx0sinx+1/2at^2

3. The attempt at a solution

x-x0=v0xt
12=(1)(23.4)t
t=.513sec

y-y0=voyt+1/2at^2
y=2.31+1/2(-9.8)(.513^2)
y=3.60m

x-x0=v0xt
x-x0=vox(cosx)t
12=23.4cos(5)t
t=.514sec

y-y0=voyt+1/2at^2
y=v0ysin(5)+1/2at^2
y=2.31

2. Feb 2, 2010

### Delphi51

I get 1.02 for that!