“Silly sprinklers” help scientists finally solve Feynman’s famous sprinkler mystery
Mathematicians have experimentally solved 'Feynman's Sprinkler Problem,' which explores how a sprinkler rotates when water is pulled in rather than pushed out. The study confirms that angular momentum of fluid flow drives the rotation, offering insights for engineering energy-converting devices.
Why it matters
Solving this long-standing physics puzzle provides practical knowledge for improving the design of turbines and other fluid-based energy systems.
Every summer, lawns fill with colorful "silly sprinklers," whose looping and twisting tubes send water spraying in unusual patterns. Their designs may look playful, but researchers have now used these backyard devices to investigate a serious and decades-old question in physics.
The mystery is known as Feynman's Sprinkler Problem. It asks what happens when a sprinkler operates in reverse, pulling water into its arms instead of forcing water outward. By building and testing sprinklers with a variety of shapes, a team of mathematicians has now produced a clear experimental answer. Their results also offer broader insight into how moving fluids push, twist, and rotate physical structures.
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