Water Bucket Momentum Question

1. Jul 8, 2010

ortegavs

1. The problem statement, all variables and given/known data

A bucket full of water is slid across a sheet of ice in the rain. As the bucket fills, what happens to its velocity and its momentum? ( assume no friction)

2. Relevant equations

P=mv

3. The attempt at a solutionI reasoned that since the bucket gained mass it gained momentum and that since no force acted on the bucket in the horizontal direction v stayed constant.

Answer given: velocity decreases and momentum remains constant
Does this means momentum is a conserved quantity?

2. Jul 8, 2010

pgardn

What would happen if instead, the bucket was moving along at a constant velocity and without interfering with the bucket or the ice, you were able to suck water out of the bucket?

3. Jul 8, 2010

rock.freak667

Yes momentum is a conserved quantity.

If initially it has momentum p=m1v1

and after it has p=m2v2

Then m2v2=m1v1 or v2 = (m1/m2)v1

So if m2 increases then v2 will decrease.