A tennis ball is served horizontally from 2.4m above the ground at 30m/s

a) the net is 12m away and 0.9m high ... Will be ball clear the net?

b) where will the ball land ... ?

The time for the ball to reach the net:

distance = speed x time

t = 12/30

t = 0.4 seconds

a) Height of ball after 0.4 seconds:

h = 2.4 - ut - 1/2 at²; u = 0

h = 2.4 - 1/2 x 9.81 x (0.4) ²

h = 1.62 m

h > 0.9 m so the ball will clear the net.

b) The time taken for the ball to hit the ground:

2.4 = 1/2 x 9.8 x t²

t = 0.70 seconds

Distance = speed x time

d = 30 x 0.7

d = 21 m

The ball lands 21 m away.