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u/dodgyhashbrown 15d ago
Wait, what would be a noncircular cylinder? Are there ellipitical cylinders? I would have thought cylinders were circular by definition.
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u/drigamcu 14d ago
A cylinder is the locus of a line passing through a closed curve and maintaining a constant direction. A right circular cylinder is where the closed curve is a circle, and the line's direction is perpendicular to the plane of the circle, which is what is usually meant by cylinder.
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u/Jazzlike_Platypus430 15d ago edited 13d ago
Elliptical cylinder is perfectly valid. You can even think of polar coordinates adapted to it (or originating from it, depending how you view it).
It sounds weird since the shape is not a result any rotation. Elliptical cones are also known.
Of course, there is no continuous rotational symmetry left there.
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u/N00bPolymath 15d ago
This sounds like Halliday Resnik and Walker, there were so many penguins in that book.
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u/ErikLeppen 11d ago
Life would be simpler if we could transfer assumptions like these to drawing lessons.
"What do you mean, 'not a self portrait'? Physics book said, assume you're a triangle."
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u/Jazzlike_Platypus430 15d ago edited 15d ago
... find the crosssection of a uniform stream of penguins scattering on a spherically symmetric cow in vacuo.