# Strength of material, how to know it is compressio or tension?

1. Feb 1, 2010

### aiklone1314

1. The problem statement, all variables and given/known data
May i know how to know boom and rod, which is in tension and compression?
http://img7.imageshack.us/img7/5728/16203309.gif [Broken]
http://img7.imageshack.us/img7/2595/57134603.gif [Broken]

2. Relevant equations

3. The attempt at a solution

Last edited by a moderator: May 4, 2017
2. Feb 1, 2010

### CFDFEAGURU

The answer is right in front of you. Look at the directions the forces are acting on each part.

Thanks
Matt

3. Feb 1, 2010

### CJSGrailKnigh

When you're asking for the strength do you mean the Young's Modulus because I don't see enough information to calculate stress and certainly not strain.

4. Feb 1, 2010

### CFDFEAGURU

This is just a force balance problem in statics. You arent required to calculate the stresses and/or strains.

You could easily calculate the stress in the rod if you wanted to because the diameter of the rod is given.

Thanks
Matt

5. Feb 2, 2010

### aiklone1314

i know, but the question is at first comes without the second picture i had uploaded rite?
then how can i know whether it is compression or tension with just the question(the 1st pic i uploaded)?

6. Feb 2, 2010

### pongo38

Imagine the behaviour of the structure if CB is cut. What happens to the distance CB?