# physics

posted by Sasha

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. Anonymous

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

## Similar Questions

1. ### physics

Two balls are connected by a string that stretches over a massless, frictionless pulley. Ball 1 has a mass of 0.45 kg and is held 0.74 m above the ground. Ball 2 has a mass of 5.7 kg and is held 0.88 m above the ground. When the balls …
2. ### physics

a tennis ball is dropped from 1.30 meters above the ground. it rebounds to a height of 1.00 meters. How do I find with what velocity does the ball hit the ground. With what velocity does it leave the ground, and if the tennis ball …
3. ### physics

A tennis ball of mass 100g is dropped from a height of 40m.It hits the ground and bounces back to a height of 30m after an impact of 0,01s.Ignore the air resistance .what was the velocity of the ball when it hit the ground ?
4. ### Physics

A tennis ball is dropped from 1.80 m above the ground. It rebounds to a height of 1.00 m (assume down to be negative). (a) With what velocity does it hit the ground?
5. ### Physics

The Colliding Balls: A ball is released from rest at a height h above the ground. The ball collides with the ground and bounces up at 75% of the impact speed the ball had with the ground. The collision with the ground is nearly instantaneously. …

He drops a ninja ball device from a height of 10.0m. The mass of the enter device is 190g and the mass of the top (smallest) ball is 2.90g A) calculate the momentum of the device as it hits the ground (ignore air resistance) I know …
7. ### Physics

You toss a tennis ball straight upward. At the moment it leaves your hand it is at a height of 1.5 m above the ground, and it is moving at a speed of 7.8 m/s. (a) How much time does it take for the tennis ball to reach its maximum …
8. ### preparation

a ball of mass .1kg initially at rest is dropped from height of 1 meter.ball hits the ground and bounces off the ground.upon impact with the ground its velocity reduces by 20%.the height to which the ball will rise is?
9. ### physics

A ball of mass 0.1 kg, initially at rest, is dropped from height of 1 m. Ball hits the ground and bounces off the ground. Upon impact with the ground, its velocity reduces by 20%. The height (in m) to which the ball will rise is:
10. ### physics

A ball of mass 0.1kg is dropped from a height of 8m into a hard floor and bounces back to a height of 2m calculate the velocity when the ball hits the ground, the velocity with which the ball leaves the ground,the momentum when the …

More Similar Questions