Physics
posted by natali on .
A ball of mass 0.15kg is dropped from rest at a height of 1.25m. it rebounds from the floor to reach a height of 0.960n. what impulse is given to the ball from the floor?
i don't have a clue where to start.
i know impulse is constant force x change in time or time elapsed, but i don't any time with this question any help?

Impulse= change of momentum
Remember momentum is a vector, it was downward as the ball fell, and upward as it rebounded, so it changed sign
Impuls= finalmomentum initialmomentum
=m(vfvi)
Now one has to deal with the heights.
Using energy concepts to change between heights and velocities...
v^2=2gh so v= sqrt (2gh)
Impulse= m*sqrt[(2g)(.960+1.25)]
Notice carefully the sign in the last parenthesis, you need to understand why it is positive. 
do you do high school physics