physics @ elena
posted by emily on .
can you please help me with this one
At serve, a tennis player aims to hit the ball horizontally.
part a)What minimum speed is required for the ball to clear the 0.90mhigh net about 15.0m from the server if the ball is "launched" from a height of 2.50m ?
part b)here (relative to server) will the ball land if it just clears the net?
part c)Will it be "good" in the sense that it lands within 7.0m of the net? yes or no ?
part d) How long will it be in the air?

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Posted by clarissa on Sunday, April 22, 2012 at 6:03pm.
At serve, a tennis player aims to hit the ball horizontally.
part a)What minimum speed is required for the ball to clear the 0.90mhigh net about 15.0m from the server if the ball is "launched" from a height of 2.50m ?
part b)here (relative to server) will the ball land if it just clears the net?
part c)Will it be "good" in the sense that it lands within 7.0m of the net? yes or no ?
part d) How long will it be in the air?
ap physics  Damon, Sunday, April 22, 2012 at 6:35pm
Hi = 2.5
h = .9
u = constant = 15/t
v = g t
.9 = 2.5 + 0*t 4.9 t^2
so
t^2 = 1.6/4.9 = .3265
t = .5714 second
u = 15/t = 26.25 m/s
onward by yourself 
I saw that u aready did this, but when I calcuated everything my answers were still wrong

Sorry. I did it again and still got u = 26.25 m/s

To do the ground, repeat that calculation with h = 0 instead of .9
use the same u
part c, subtract 15 m
the way I did part b, you have t total