# Dropped tennis ball! Please help me to solve this problem... thanks a lot?

After you drop a tennis ball of 0.5 kg from rest at a height of 3.8 m onto a hard floor, find the fallowing:

a) what will be the speed of the ball at the instant of contact with the floor?

Thank you!

v=8.63m/s

b) what force does the floor exert on the ball?

(f)=?N

c) Over what time does the force act in bringing the ball to rest?

(delta)t=?s

Thanks!

### 2 Answers

Relevance

- 1 decade agoFavorite Answer
a) 8.63*.5

b) same answer as a bc of = but opposite

c) (.5)*((3.8)/delta(t))=8.63 solve for t

- 1 decade ago
Energy before the drop should equal energy after drop(release and motion of ball)

m=mass

g=9.81m/s^2

h=height from floor

v=velocity

Energy before:potential energy: mgh

Energy afterwards: kinetic energy: 1/2 mv^2

mgh=(1/2)mv^2

solve for v

v=sqrt(gh/.5)

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