TBR stress

[Sonyfan08]

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If a think wire of steel was hung vertically, is it the tension or compression stress one has to consider.

I thought it was tension, but the answer in the back says it's compression..

 

[costales]

Okay, it's compression because say, for simplicity, you divide the wire in three pieces, A on top of B on top of C, and just look at the forces on B. There are three forces on B: the weight of B, the weight of A which acts DOWN, and the weight of C which acts UP (the contact/restoring force). So there are two forces pushing "inward" on B, so you have compression. Now divide the wire further and further and you have a zillion little pieces named B. You get the idea.

 

[geeyouknit]

Okay, it's compression because say, for simplicity, you divide up the wire into three pieces, A on top of B on top of C, and just look at the forces on B: there are three forces on B: the weight of B, the weight of A which acts DOWN, and the weight of C which acts UP (the contact/restoring force). So there are two forces pushing "inward" on B, so you have compression.

By this logic, isn't there tension on A (weight of B and C) and on B(weight of C)?

 

[costales]

By this logic, isn't there tension on A (weight of B and C) and on B(weight of C)?

True. I'm just trying to justify the "official" answer... I think the book is wrong, or else there is more information I don't know about. I'm going to revert to my previous answer before edit: Pure tension.