How do whips break the sound barrier

Snapping a towel in the changing room is dangerous—you could, in all seriousness, take someone's eye out. The reason it's so dangerous has partly to do with the speed the end of the towel is traveling. Like a bullwhip, it goes very fast indeed. In , a group of students at North Carolina School of Science and Mathematics set out to prove that a properly whipped towel could break the sound barrier.

They rigged up a high-speed photography kit that would allow them to measure the distance the tip of the towel was traveling at the moment they thought the barrier would be broken.

After the experiment, it seemed like they had managed to break the barrier—but the students felt their results were inconclusive. So they tweaked the experimental setup and, according to some sources, swapped the towel for a cut down bedsheet which eventually allowed them to break the sound barrier. Here's an odd one to finish with. According to one study , when a rock or other such object is dropped into water, an hourglass-shaped cavity of air is created, which then ejects the air at speeds faster than the speed of sound.

It's claimed that the whip crack is actually a sonic boom. This sonic boom is supposed to appear when the very tip of the whip moves at faster than the speed of sound, and so breaks the sound barrier. The speed of sound is pretty close to around to 1, kilometres per hour, so how can you move the tip of a whip at that speed besides the fact that you've got a long lever arm? One theory is based on the fact that the whip is tapered from the handle to the tip. When you move the whip handle, you start a wave heading towards the tip.

The wave has a certain amount of energy. This energy depends upon the speed of the wave, and the mass of the whip that it is moving in each instant. As the wave gradually moves down into the narrow region, it's moving less mass.

He notes that even though some parts of the whip travel at greater speeds, "it is the loop itself that generates the sonic boom. Although the whip's tip has lost the distinction of being the source of the menacing crack, it is still a force to be reckoned with: according to Goriely's calculations, "the tip can reach speeds more than 30 times the initial speed [of the whip]. Already a subscriber? Sign in.

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