# Homework Help: Free body diagram : Compression and Tension

1. Apr 19, 2007

### alchemphy

P, Q, R, S are light rods attached to the wall with a force W acting at that point in the figure.
Please explain whether Compression or Tension is acting on them respectively by using Free body diagram and proper explanation.

Can I resolve W in this way so that we have a force in the direction of P and parellel to R??
Following that, we know that P is under tension and R is under compression.

Thanks.

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2. Apr 19, 2007

What do you mean by "resolve W"? It is sufficient to look at node A and it's equilibrium conditions.

3. Apr 19, 2007

### ghost_301

Since you are talking about the FBD, I think you have to draw out a FBD with reaction force at fixed support on the wall in order to explain whether is tension or compression of each members. Not 100% sure though.

4. Apr 19, 2007

### rootX

I ain't know if I am right, but I think thinking as if force is fluid and can be shared might help. Like Point B is pushing the rod R upwards, and pulling the rod Q downwards. Point A pulls the rod P towards right, and the point B; this one's little complex. Like it starts from the rod R. The rod R pushes the point B downward, and thus point B compresses the rod S, and pulls the rod Q..

Anyhow, I think you may resolve the problem if try this way