# Homework Help: Surface tension associated with acceleration and change of momentum

1. Nov 27, 2009

### pollalis

1. The problem statement, all variables and given/known data
I have an experiment which is described as: Float a water-soaked ping pong ball in a can of water held more than a meter from a rigid floor. Then drop the can. What happens to the ball as both drop (and what does his say about surface tension)? More dramatically, what happens to the ball, and why, when the can makes impact with the floor?

2. Relevant equations
acceleration: F=ma --> a=F/m
surface tension: γ=F/L (and to combine with the acceleration: (F=ma) so γ=ma/L
momentum in combination with surface tension: γ=Δρ/Δt*L

3. The attempt at a solution
When you do the experiment, the ball at the beginning is floating, when the can is dropped the ball comes out of the water for the free fall and then when the can comes crashing against the floor the ball goes in the water and then out, floating again on the surface.
So, the surface tension during the free fall decreases. But what happens after?