Here's What It Takes to Shatter Glass With Speakers

What better way to demonstrate the science of sound than by breaking stuff? For the latest installment of the new Tested web series Simple Feats of Science, host Kishore Hari and Zeke Kossover from San Francisco's Exploratorium conducted an experiment to see if basic car speakers could break a pane of glass. Using a custom-built speaker box and an audio device playing barely audible, low-frequency tones, the duo demonstrate how sound waves work without doing damage to their ears in the process.

This isn't the typical experiment involving wine glasses and high-pitched sounds. In the video above, Kossover explains how his team's version is different. "Breaking glass with sound is incredibly cool, however that high-pitched sound is really close to the most sensitive part of your hearing so it sounds super loud," he said. Those experiments are also difficult to do because of the strength of the glasses required, he added.

Instead, Kossover positioned the speakers in his custom box so that they faced opposite directions, which created pulses of air pressure inside the box's three chambers. The box is sealed so that the pressure only has three ways to escape (through three holes in the top). Kossover then gradually lowered the frequency until he found the sweet spot—the resonant frequency of the glass–causing it to break.

Check out the full experiment above and head to the Tested YouTube page for more cool science.

[h/t Tested]

© 2017 USPS
Pop Culture
Speedy Delivery: Mister Rogers Will Get His Own Stamp in 2018
© 2017 USPS
© 2017 USPS

USPS 2018 Mister Rogers stamp
© 2017 USPS

After weeks of mailing out this year’s holiday cards, postage might be the last thing you want to think about. But the U.S. Postal Service has just given us a sneak peek at the many iconic people, places, and things that will be commemorated with their own stamps in 2018, and one in particular has us excited to send out a few birthday cards: Mister Rogers.

In celebration of the 50th anniversary of Mister Rogers’ Neighborhood, Fred Rogers’s groundbreaking PBS series that the USPS says “inspired and educated young viewers with warmth, sensitivity, and honesty,” the mail service shared a mockup of what the final stamp may look like. On it, Rogers—decked out in one of his trademark colorful cardigans (all of which were hand-knitted by his mom, by the way)—smiles for the camera alongside King Friday XIII, ruler of the Neighborhood of Make-Believe.

Though no official release date for Fred’s forever stamp has been given, Mister Rogers is just one of many legendary figures whose visages will grace a piece of postage in 2018. Singer/activist Lena Horne will be the 41st figure to appear as part of the USPS’s Black Heritage series, while former Beatle John Lennon will be the face of the newest Music Icons collection. Sally Ride, the first American woman in space, will also be honored.

Can You Spot the Christmas Pudding?

Whether it’s a sheep hanging out with Santa Claus or a panda bear hiding among some snowmen, regular Mental Floss readers know that hidden picture brainteasers are one of our favorite things. And the optical experts at have released a delicious one, just in time for Christmas. Somewhere in the midst of all these holiday-themed goodies above, there’s a holiday pudding just waiting to be discovered. Can you spot it? Your time starts … now.

If you give up, or are the kind of person who reads the last page of a book before the first one and just wants to know the answer, scroll down to see where it’s hiding.



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