Mathematician Calculates Rotational Speed of Fidget Spinner in Fidgets Per Second

iStock // fullempty
iStock // fullempty

How fast does a fidget spinner spin? It's a simple question with a simple answer, but a complex path to that answer. The issue lies in analyzing an extremely fast-moving object with simple tools, like a smartphone.

In the video below, mathematician Matt Parker turns to a spectrogram sound-analyzing app to solve this problem. Spectrograms are visual representations of sound, allowing the viewer to pick out certain frequencies within an audio clip and measure their intensity. By figuring out the sound the fidget spinner makes, Parker can sort out how many Hertz (cycles per second) the spinner is rotating at.

The first task is making the spinner itself stable, so it's easy to spin and becomes a reliable target for audio recording. Parker attaches the device to a drinking glass, and mounts the smartphone above it, with the microphone pointed at the edge of the spinner. Then by blowing the fidget spinner with compressed air, the mathemagic happens.

Parker calculates the absolute speed of the tips of the fidget spinner, as well as the speed of the spinner in revolutions per minute—the latter is roughly 3750 rpm! (For comparison, a typical car engine runs around 2000-3000 rpm when cruising.) The video is full of further analysis and methodology.

Tune in for some delightful applied mathematics...and be sure to wear your safety gear!

Incidentally, Parker used the SpectrumView app, though there are others like it. He also posted a screenshot of the spectrogram, as seen in the video, in case you want to test your own spinner.

The New Apple Watch SE Is Now Available on Amazon

Apple/Amazon
Apple/Amazon

Apple products are notorious for their high price tags. From AirPods to iPads to MacBooks, it can be difficult to find the perfect piece of tech on sale when you are ready to buy. Luckily, for those who have had their eye on a new Apple Watch, the Apple Watch SE is designed with all the features users want but at a lower starting price of $279— and they're available on Amazon right now.

The SE exists as a more affordable option when compared to Apple's new Series 6 line of watches. This less expensive version has many of the same functions of its pricier brethren, except for certain features like the blood oxygen sensor and electrical heart sensor. To make up for the truncated bells and whistles, the SE comes in at least $120 cheaper than the Series 6, which starts at $400 and goes up to $800. The SE comes with technical improvements on previous models as well, such as the fall detection, a faster processor, a larger screen, water resistance, and more.

Now available in 40mm ($279) and 44mm ($309), both SE models offer a variety of colors to choose from, such as sliver, space gray, and pink. If you want cellular connection, you’ll have to pay a bit more for the 40mm ($329) and the 44mm ($359).

For more, head to Amazon to see the full list of offerings from Apple.

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100 Fascinating Facts About Earth

The best Spaceball.
The best Spaceball.
NASA

Did you know that there’s a place in the South Pacific Ocean called Point Nemo that’s farther from land than any other point on Earth? So far, in fact, that the closest humans are usually astronauts aboard the International Space Station. (And by the way: The map you’re about to look for Point Nemo on might not be entirely accurate; a certain amount of distortion occurs when trying to depict a 3D planet on a 2D surface.)

In this all-new episode of The List Show, Mental Floss editor-in-chief Erin McCarthy is journeying to the center of the Earth, and visiting its oceans, its atmosphere, and even space, in search of 100 facts about our endlessly fascinating planet.

The subjects that fall under the umbrella of “facts about Earth” are nearly as expansive as Earth itself. Geology, biology, astronomy, and cartography, are all fair game—and those are just a few of the many -ologies, -onomies, and -ographies you’ll learn about below. 

Press play to find out more Earth-shattering facts, and subscribe to the Mental Floss YouTube channel for more fact-filled videos here.