# Homework Help: Simply to 2-d

1. Oct 4, 2009

### jmora

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

So I have a physics problem which I can't do (I am in ap physics c by the way). I only need help with the idea as I cannot find anyway to do the free body diagram.

So the question is "A crate slides down an inclined right-angled trough. The coefficient of kinetic friction between the crate and the trough is μk. What is the acceleration of the crate in terms of μk, θ, and g? Include a labeled force diagram for the crate. " my teacher worded it funny. The problem is the ramp has two sides that are applying a force of normal and they are joined at a 90 degree angle (so the box first perfectly). Hard to describe but it goes into all three dimensions any angle you look at it (imagine a slide shaped up like v with angle being 90 degrees and sliding down on it). The problem is that I cannot do force vectors without having to do some sort of 3d model, which I'm not supposed to do (more like I don't know how to do). Again I don't need the answer I am just having a lot of trouble with the concept as I have never encountered it before.

2. Relevant equations

None

3. The attempt at a solution

I've put toothpicks together, looks like a very ugly 3-d fbd.

EDIT: I just realized that i just joined and didn't really bothered to look around thoroughly. So if this is in the wrong place sorry in advance

2. Oct 4, 2009

### bobquantum

Well, you might want to complete a better versoin of the three -d diagram, no offense. From there, you can draw all the vectors and having a visual often helps with physics. If all comes to worst, then there is computer software online that you can use.

Hope this helps,
BOB

3. Oct 4, 2009

### jmora

The thing is that we have never talked about 3-d fbd diagrams. It should all fit into on or more 2-d diagrams. I tried making three separate ones (for the two surfaces) but I just can't get it once it comes to the box. And online software? Do you have link? Thanks