# Homework Help: A Speed Problem

1. Sep 5, 2007

### NeRdHeRd

1. A 9.0-kg box of oranges slides from rest down a frictionless incline from a height of 5.0m. A constant frictional force, introduced at point A, brings the block to rest at point B, 19 m to the right of point A. What is the speed of the block just before it reaches point A?

Can anyone point me in the right direction. I'm having a difficult time figuring out where to start solving this problem.

2. Sep 5, 2007

### bel

Well, how about $$E_{k} = \frac{1}{2}mv^2$$?

3. Sep 5, 2007

### learningphysics

Is any other information given? The length of the incline... or the angle of the incline? information seems missing to me... Is B at the bottom of the incline?

Last edited: Sep 5, 2007
4. Sep 5, 2007

### NeRdHeRd

This is the only information given in the problem. I thought the same thing. to me there seems to be missing information.

5. Sep 5, 2007

No picture?

6. Sep 6, 2007

### Staff: Mentor

I imagine that point A is at the bottom of the incline and that points B and A are at the same height. (But why do we have to guess?)

7. Sep 6, 2007

### learningphysics

But then the frictional force is unnecessary for the problem. :tongue2:

8. Sep 6, 2007

### Staff: Mentor

Certainly the frictional force is unnecessary for this question. But I'm guessing that this is just the first of several questions. (But if this problem is all there is, you're right, of course. :tongue:)

9. Sep 6, 2007

### learningphysics

Ah... that's a good point. I didn't think of that.