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Why coasters are a bad frisbee

Use them as spinners, tear them into pieces, flip them into groups and hold them back with the same hand, or scribble on the back of the first impulse for a great solution to the world’s problem – in the pub, Swiss coasters offer options for using an army knife-like scope. The fact that sometimes a bottle or a glass appears on it can easily be called a miracle.

However, anyone who has ever tried to promote such a beer mat into a primitive Frisbee with a confident swipe of the arm while sipping on a drink knows that the famous pub game can’t do it all. After a short flight, she always turns on her side. If you’re lucky, you’ll roll a bit afterwards and you can pretend that was the intention the whole time.

Three physicists wrote recently that, unfortunately, there is no longer an honor to be earned. Not on the back of a beer, by the way, but On the scientific publishing site Arxiv. title say? Beer coasters are a bad frisbee.

They calculated it after about 0.45 seconds. Then the interaction between rotation about the vertical axis and gravitational attraction causes a gravitational pull on the felt that does not engage perfectly in the center, but deviates slightly from the center, on the side where the felt flies. The result is what generations of frustrated cookers have seen with their own eyes: a coaster crumble.

By the way, this fate affects not only beer coasters, but every round object thrown. If you want to throw away CDs or DVDs for any reason, you will face exactly the same problem. The reason the Frisbee spins steadily and predictably through the air is the curved edges. These alter the sum of air motions and other forces in such a way that even a dog can safely toss such a frisbee out of the air after a predictable flight.

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In order to test their mathematical predictions for the somewhat less cool beer felt flight behavior with the grim reality, the physicists decided to start throwing away beer mugs. To this end, they built a beer felt launcher that could fire discs with a predetermined speed and spin. They captured the result with high-speed cameras.

And guess what: Even with this reliable casting machine, felt pads always tip over after about 0.45 seconds. So, it’s definitely not down to your heady throwing style if your beer rug bounces quickly on the bar floor.

Finally, in their professional article, the authors also briefly consider the real victims of the harsh laws of beer physics. “Our sincerest apologies to anyone whom Coaster bumped into, whether it was an unlucky pitch or because this research has led others to make foolish experiments.”

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