I don't think you need Newton here. You just need your definition of momentum, as well as a little dimensional analysis to solve this problem. Think this way:
Do you follow?
(think this is the right section).
I'm stuck on a question in a physics paper:
Water of density flows out of a garden hose of cross-sectional area at a rate of per second. How much momentum is carried by the water leaving the hose per second?
I think it may have something to with and . Maybe somehow using the rate of flow to work out acceleration and density to find mass but I'm clutching at straws there.
edit, oh and probably