Why a squeezed ruler bows sideways: Euler's buckling and the hollow tube
30seconds
Squeeze a ruler between your palms and it doesn't crush: it bows sideways and gives way. That's buckling, and it decides how slender a column can be.
Euler worked out the threshold in 1757: the load a column can carry falls with the square of its length, and depends on stiffness and shape, not on how strong the material is. Play with a steel rod below: stretch it, hollow it out, clamp its ends, and see which fails first.
Deep dive · 4 min
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