# physics

a tennis ball of mass 20g is released from rest at a height of 4m above the ground. on hitting the ground,it raises to a height of 3m.find the velocity with which it hits the ground.

1. 0
2. 1
1. falls 4 meters
v = -g t
h = Hi - (1/2) g t^2
g = 9.81 m/s^2
so

0 = 4 - 4.9 t^2
t^2 = 4/4.9
t = .904 seconds

v = -9.81 * .904 = -8.87 meters/second

posted by Anonymous

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