# Help solving problem

1. May 11, 2007

### shanegarner

:yuck: How much pressure would it take to push the water out of a 6000 feet tall pipe full of water that is 3.5" inside diameter?

2. May 11, 2007

### Staff: Mentor

Is this a homework problem? If so, I can move it to the appropriate Homework Help forum.

To address your question, what is the equation that relates force, pressure and area? What is the density of water?

3. May 11, 2007

### shanegarner

no, my friend is trying to figure out what pump he needs to push the water out of this pipe...what head pressure..

4. May 11, 2007

### Staff: Mentor

Fair enough. The pressure that will be required of the pump is a bit higher than the pressure that the water column is exerting on the bottom of the pipe. Imagine that the water column is supported just by a disk at the bottom that is 3.5" in diameter. What is the weight of the water on that disk (water density multiplied by the volume of the water column), and what is the surface area of the disk? Make sure to keep all of your units consistent, and you will have the pressure of the water column at the bottom. Then pick a pump that can generate a higher pressure, and pump away.

5. May 11, 2007

### Astronuc

Staff Emeritus
6. May 11, 2007

### vanesch

Staff Emeritus
Everybody here is assuming that the pipe is vertical... but 6000 feet, that's about 2000 meters, right ? Doesn't sound reasonable to me. You wouldn't want to pump that in one single go, would you ?

So I think that the OP is talking about a horizontal pipe, and the friction losses or something.

7. May 11, 2007

### Staff: Mentor

It says 6000 feet tall in the OP. Besides - if it were horizontal, it wouldn't require any pressure at all (as long as you aren't concerned about the flow rate, which the OP doesn't specify...).

Anyway, yes, you wouldn't want to pump that all in one shot (and probably couldn't even if you did).

8. May 12, 2007

### rcgldr

By the way, pipe diameter doesn't matter, just pump outlet diameter. The issue is pressure, not force.