ELI5: why is a hollow metal tube nearly as strong against bending as a completely solid rod of the same material, even though theres way less metal in it
was walking past a construction site the other day and noticed basically every structural element was hollow tubes, scaffolding, support beams, even the crane parts. my gut instinct was always that solid = stronger but clearly engineers dont think so.
i understand the hollow version is lighter and saves money on raw materials which is great but thats not the part thats messing with me.
what i cant figure out is how gutting the entire inside of a piece of metal barely seems to affect how much force it can take before bending. like the middle is literally just air. how is air contributing to the strength of anything
is it something about how the forces are distributed across the shape? ive heard the phrase "moment of inertia" thrown around while researching and playing on my phone but never seen it explained in a way that actually made sense. feels like there should be a really satisfying explanation for this that doesnt involve math