I am wondering which one is the strongest between a steel rope and a steel bar with same diameter and made of the same steel?
EDIT : The test could be: attach rope/bar to ceiling and suspend a mass until it break
EDIT2 : Can I have also some order of magnitude? For example, is the rope 2 times stronger than the bar?
Best Answer
I assume the total cross section of the wires in the rope is equal to the cross section of the steel bar. Since there is some space between the fibers, the rope will have a larger diameter.
If the fibers in the rope were all straight and you were careful to pull equally on each fiber, the bar and rope should be equally strong. But they typically won't be.
Suppose one fiber is a little weaker than the others, and breaks first. Now the rest have a heavier load.
In practice, you can buy copper wire in single strand or multiple strand forms.
The advantage of multiple strands is flexibility. You use them in cables you plug in often. Flexing them too much can break individual fibers, and eventually break the wire.
The advantage of single strand is durability. Wires inside walls are single strand because they are inconvenient to replace. They are seldom handled, so stiffness isn't a problem.