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The shower isn't supposed to be a dangerous place, but once you turn on the water, you might be attacked by your shower curtain. But don't blame the curtain! Blame physics!

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[ INTRO ].

The shower isn’t supposed to be a dangerous place. Put down some of those grippy things on the bottom of the tub and avoid being in a 1960’s horror movie, and you should be safe.

But sometimes, despite these precautions, you find yourself under attack by the flimsiest of foes – the shower curtain. And that’s not because a nefarious poltergeist is hell-bent on ruining your shower. Probably.

Scientists think it’s all an unfortunate coincidence of physics. The standing shower was a marvelous invention that allowed people to use less water when bathing. But ever since someone had the bright idea of adding a cloth for privacy, we've been plagued by lightweight curtains clinging to us and wrapping around our legs while we're trying to suds up.

Unless you have a heavy curtain or one with magnets at the bottom, you know exactly what. I'm talking about. It’s such a problem that a number of scientists and engineers have tried to figure out what’s going on, and there are now several explanations for why shower curtains assault us as soon as we turn on the faucet.

At first, people thought it was simply that the hot water warmed the air in the tub or stall, which then rose— pulling colder air, and the curtain, in from the bottom to replace it. But the effect still happens in cold showers, so something else has to be at play. So other scientists pointed to Bernoulli’s Principle.

Named after physicist Daniel Bernoulli, it explains the inverse relationship between the speed of a fluid and the amount of pressure around it. In this case, that “fluid” is actually the air in your shower stall. The fast-moving water from the shower head causes the air inside the stall to churn and speed up.

When this happens, the air pressure inside the shower drops, creating a very slight vacuum that can suck lightweight objects into the stall. And then—lucky you—shower curtain hugs! Awww!

But not all scientists are convinced Bernoulli’s Principle fully explains this annoying phenomenon because it doesn’t take into account the water droplets themselves— just the air around them. Using computer modeling, a mechanical engineer at the University of Massachusetts discovered that the shower’s water spray can create a horizontal vortex– kind of like a sideways hurricane. And that makes the center of the shower vortex an area of low pressure, much like the eye of a hurricane, which causes the curtain to be sucked in toward you.

The stronger the water pressure from the shower head, the more likely this is to happen. This might not be the most /ground-breaking/ discovery in physics of the twenty-first century, but it does offer up another cool explanation for our shower curtain woes. So, next time you’re enjoying a shower and the curtain attacks you – remember, there are no malicious forces at work.

It’s just physics. Thanks for asking about this, Valerie S.! And thanks to all our patrons that voted for this question in our poll.

If you have questions like this you want us to answer, or you just want to help support. SciShow, you can learn more about becoming a patron at [ OUTRO ].