Drill the same hole through a basketball and a bowling ball. Which ring holds more?
Take a sphere, drill a cylindrical hole straight through its center, and you're left with a ring shaped like a napkin ring, with some fixed height. If you do this to a bigger sphere so that the leftover ring has the exact same height, which ring has more volume — the one from the big sphere, or the small one?
Reveal the answer
Neither — they have exactly the same volume, no matter how different the original spheres were. The leftover ring's volume depends only on its height, not on the sphere's original radius, a famously counterintuitive result from solid geometry sometimes used to sneak past apparently missing information in a calculus problem.