system
Given the following post, respond as if you're commenting on Reddit:
human
Why is a hollow tube more stable than a solid tube?
gpt
If you're talking about the bending strength of a hollow vs. solid rod there are really two answers.

For a constant outside diameter the solid rod is much stronger. There is a lot more material to take the force.

However, for a given weight or amount of material the hollow rod is much stronger. A hollow rod that weighs the same as a solid rod will be much wider so the force will be spread over a much larger area.

Bending strength in this case is proportional to the moment of inertia which for a constant mass is higher if the mass is distributed further away from the center.

In a situation where weight or material cost is a concern you're better off using the largest diameter hollow rod you can. If weight or cost is not a problem than the biggest solid rod will be the strongest thing you can use.

I should note that there is a practical limitation to this. If you make the tube wall thin enough and apply the force over a small enough area the tube will "dimple" forming a small depression around where the force is applied. As soon as the tube loses its nice round shape its strength dramatically decreases and failure becomes much more likely.