Average force between an object and non-movable object?

[sirfinklstin]

Homework Statement

A golf ball of mass 41.8 g is dropped from a height h = 1.41 m onto a hard floor and bounces back to exactly that same height. What is the average force (in N) on the ball during the 0.012 s that it was in contact with the floor?

Homework Equations

Impulse = Ft
Impulse = m(Vf - Vi)

The Attempt at a Solution

I am not quite sure how to proceed with this problem, because I am completely clueless as to how I should go about calculating the change in velocity, because if the ball returns to the same height, (no friction of air resistance) then arent the Vi and Vf both = 0?

 

[tiny-tim]

Hi sirfinklstin!

A golf ball of mass 41.8 g is dropped from a height h = 1.41 m onto a hard floor and bounces back to exactly that same height. What is the average force (in N) on the ball during the 0.012 s that it was in contact with the floor?
…
how I should go about calculating the change in velocity, because if the ball returns to the same height, (no friction of air resistance) then arent the Vi and Vf both = 0?

Yes, but you want the two velocities at ground level.

 

[sirfinklstin]

How would the velocities be calculated? 0 + (9.8 m/s)(1.41m)?

 

[tiny-tim]

How would the velocities be calculated? 0 + (9.8 m/s)(1.41m)?

what? v = as ??