Why Does My Shower Curtain Liner Attack Me?

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iStock

For most of us, showers are a time to block out external stimuli and enjoy a moment to ourselves. The blissful monotony can often lead to creative inspiration or new ideas. Celebrated screenwriter Aaron Sorkin once said he takes up to six showers a day to help unblock his mind and resolve story problems.

But not all showers can make us part of the wealthy Hollywood elite. Some showers can become exercises in dread and frustration. We’re referring to the persistent attack of the shower curtain liner.

Liners have a tendency to billow inward during showers, enveloping themselves around our calves and forcing us to swat them away. As problems, go, it’s fairly innocuous. But that doesn’t mean science hasn’t tried to understand the physics behind the phenomenon.

Back in 1938, Popular Science theorized that liners were behaving badly as a result of air currents. When hot air from the warm water rises, cold air around the tub seeks to replace it, causing the liner—which is in between—to grow agitated. This explanation seemed to satisfy people for a while, until someone pointed out that the liners tend to move even during a cold shower.

Others believed the liner was acting as a result of Bernoulli's principle, which states that air pressure around fluid decreases when the fluid is moving quickly. With a difference in air pressure inside and outside the tub, the liner will move.

In 2001, someone finally had the means and motivation to examine this theory more closely. David Schmidt, an assistant professor at the University of Massachusetts Amherst, used computer software developed to examine fluid spray to assist in diesel and aircraft engines to put Bernoulli's theory to the test. This being 2001, it took his home PC two weeks to run the simulation, which Schmidt programmed to replicate a typical shower (rod, curtain, liner, shower head).

Schmidt found that the shower spray created a vortex with a low-pressure region—a little like the center of a cyclone. That region is what “sucks” the liner inward. Despite the relative calm of a shower, the simulation indicated that you’re basically in the eye of a very low-level storm.

For more answers, Schmidt would probably have to consider overseeing a real-world model, but he said he doesn’t have the time or inclination to take the whole shower cyclone science thing to the next level.

That’s not quite the end of the story, though. In 2007, physics author Peter Eastwell tinkered with a shower set-up and noted that the cyclone effect was more pronounced in hotter than cooler water, and that factors like the distance of the liner from the spray affected the liner’s movement.

Clearly, more work needs to be done on this important issue. Until then, using a heavier liner or attaching weights to the bottom can prevent billowing. Alternately, you could just install a shower door. Aaron Sorkin probably has one.

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What’s the Difference Between Crocheting and Knitting?

djedzura/iStock via Getty Images
djedzura/iStock via Getty Images

With blustery days officially upon us, the most pressing question about your sweaters, scarves, hats, and mittens is probably: “Are these keeping me warm?” If you’re a DIY enthusiast, or just a detail-oriented person in general, your next question might be: “Were these knitted or crocheted?”

Knitting and crocheting are both calming crafts that involve yarn, produce cozy garments and other items, and can even boost your mental well-being. Having said that, they do have a few specific differences.

To knit, you need needles. The size, material, and number of those needles depends on the project; though most traditional garments are made using two needles, it’s also possible to knit with just one needle, or as many as five. But regardless of the other variables, one or both ends of your knitting needles will always be pointed.

While crocheting calls for a similar long, thin tool that varies in size and material, it has a hooked end—and you only ever need one. According to The Spruce Crafts, even if you hear people refer to the tool as a crochet needle, they’re really talking about a crochet hook.

crotchet hook and garment
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Part of the reason you only use one hook brings us to the next difference between crocheting and knitting: When crocheting, there’s only one “active loop” on your hook at any given time, whereas knitting entails lining up loops down the length of your needles and passing them between needles. The blog Darn Good Yarn explains that since each loop is attached to a long row of stitches, accidentally “dropping” one off the end of your needle might unravel the entire row.

Of course, you have a better chance of avoiding that type of manual error if you’re using a knitting machine or loom, which both exist. Crocheting, on the other hand, has to be done by hand. Since machines can create garments with extremely small stitches, some knit clothes can be much more lightweight or close-fitting than anything you’d be able to crochet—and knitted clothes can also be mass-produced.

When it comes to what the items actually look like, crochet stitches characteristically look more like knots, while knit stitches seem flatter and less bulky. However, materials and techniques have come a long way over the years, and now there’s more crossover between what you’re able to knit and crochet. According to The Spruce Crafts, socks and T-shirts—traditionally both garments that would be knitted—can now technically be crocheted.

knitting needles and garment
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And, believe it or not, knitting and crocheting can even be used to depict complicated mathematical concepts: see what a crocheted hyperbolic plane, Lorenz manifold, and more look like here.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

What Happens to Leftover Campaign Funds When a Candidate Drops Out?

After nearly one year of campaigning for the Democratic presidential nomination, Kamala Harris has officially bowed out of the 2020 election. She's not the only would-be president to call it quits so far. So what happens to all the leftover campaign funds when a candidate drops out?

One thing's for sure: Upset candidates can't console themselves by putting the dough toward a new yacht and sailing off to recuperate. The Federal Election Commission has strict rules about what federal candidates can and can't do with leftover campaign money, and the biggest directive is that they can't pocket it for personal use.

Here's what a campaign committee is allowed to do with any lingering cash: it can donate the funds to charities or political parties; it can contribute $2000 per election to other candidates; and it can save the money in case the candidate chooses to run again. However, those regulations don't apply to the relatively new super PACs (Political Action Committees); this is only the third election where they have played a role, and there are currently no rules to stipulate what happens to that money beyond that it cannot go to fund another federal candidate. Much of that money tends to be returned to its original donors, used to wrap up the failed campaign, or donated to back a state-level candidate. The goal, however, is always to spend all of that money.

Running a campaign is an expensive proposition—Barack Obama spent nearly $750 million on his 2008 White House bid, and in 2012 he spent $985 million on reelection while challenger Mitt Romney spent $992 million—and insufficient cash is often a reason campaigns go belly up.

As for winning (or sometimes losing) politicians, they'll often put their leftover funds toward their next race. If they choose not to run, they have to abide by the same FEC rules. Wonder why this law is in effect? Until 1993, U.S. Representatives who took office before January 8, 1980, were allowed to keep any leftover campaign cash when they retired, but a study showed that a third of Congress kept and spent millions in campaign donations on personal items like clothing, jewelry, artwork, personal travel, and dry cleaning. Embarrassed, Congress passed a law negating this custom for the House; the Senate already had provisions in place so this wouldn't happen.

In reality though, officials can usually find a way to make that cash still work for them (and state laws differ from federal ones). After Chris Christie won reelection as New Jersey's governor in 2014, his campaign was granted permission to use some of its remaining war chest to cover the legal fees Christie incurred during the Bridgegate scandal. And this was well before he dropped $26.7 million on his failed 2016 presidential bid.

An earlier version of this article originally ran in 2012.

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