# Homework Help: Momentum Problem on Water hose

1. Dec 5, 2007

### gidra

It's my first time writing on this forum, hope i'm posting in the correct section.

Problem :

A hose directs a horizontal jet of water on to a vertical wall.

What is the force on the wall, under the above conditions ? Explain.

Thanks for any replies

2. Dec 5, 2007

### Staff: Mentor

Please post the complete problem exactly as it was given.

3. Dec 5, 2007

### gidra

A hose directs a horizontal jet of water, moving with a velocity of 20ms^-1, on to a vertical wall. The cross-sectional area of the jet is 5 x 10^-4 m^2. If the density of water is 1000kg m^-3:

a) fin the rate of change of momentum as the water hits the wall, assuming that the water is brought to rest there;

b) what is the force on the wall, under the above conditions? Explain

4. Dec 5, 2007

### Staff: Mentor

That's better. Hints for a: How much water hits the wall every second? What's its momentum just before it hits the wall? What's its momentum just after hitting the wall? What's the change in momentum?

5. Dec 5, 2007

### gidra

I worked out part a, i'm stuck with the theoratic part now. Can't really understand the question. Thanks for your replies btw

6. Dec 5, 2007

### Staff: Mentor

I'm not sure I understand. You completed part a? And you're stuck on part b?