# Homework Help: Tensile cables

1. Dec 10, 2017

### jonnybmac

1. The problem statement, all variables and given/known data
Why are cables thin when used as ties? Why are they not equally as thick as say struts?

2. Relevant equations

3. The attempt at a solution
Is it because when in tension the tie cannot buckle? or because when in tension it cannot shear?

Steel has the same compressive strength as tensile, so why do they differ?

2. Dec 10, 2017

### lekh2003

I have tried looking on several forums on the internet as well as some educational sites and I oddly have no clue why thin wires are better at tying. The question is now stuck on my mind.

Is there anyone working in the practical field who can shed some information on this?

3. Dec 10, 2017

### jonnybmac

I think I have cracked it thank you.

When in tension it is only loaded axially so the strength is force the over cross-section area, but in compression you have buckling that stops the member reaching its maximum strength, and that if you look at the bending equation or Euler's column formula, they both rely on the moment of inertia which is affected by shape.

4. Dec 10, 2017

### lekh2003

Thanks, I'll look into it.

5. Dec 11, 2017

### CWatters

You could look at the equations or you could play with some copper wire in your hands. See how it feels under tension and compression.