Category Archives: Video

The World's Thinnest Trampoline

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Super-stretchy jelly can take a hit

Suo’s hydrogel is made from a mixture of two polymers — alginate and polyacrylamide. Each polymer forms networks using different types of chemical bond: alginate molecules are linked together by ionic bonds, and polyacrylamide molecules by stronger covalent bonds. When the gel is stretched, hit or torn, the ionic bonds can break and reform throughout the material, dissipating energy over a wide area and causing fewer of the covalent bonds to be irreversibly ruptured. The covalent bonds hold the material together, allowing it to spring back to its original shape.

So Do You Feel Lucky, Mr. Fly?

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Seeing as this is a bug-a-salt, the most powerful salt gun in the world, you have to ask yourself one question … do I feel lucky.

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Bug-A-Salt

A little BotE calculation: flies are of order 1 cm, and salt grains around 100 microns. Scale this up to human size and it’s like being hot by a chunk of salt 15-20 mm across, or around 75 caliber. At a pretty decent clip, too. So, ouch! And several chunks, really, so (n * ouch), which is why it can do in the fly. I may have to break down and get one of these and use my slow-motion camera to measure the muzzle speed. All in the name of science, of course.

h/t to Moontanman

I Have 7207. Do I hear 9000?

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Downward Positive Cloud-to-Ground Lightning Flash Triggers Upward Positive Leaders from Towers

A positive cloud-to-ground lightning flash triggers upward positive lightning leaders to form from three television towers in Rapid City, South Dakota. Filmed at 9,000 images per second, the video shows positive leaders descending from the thunderstorm with one connecting to ground. The resulting return stroke creates a fast electric field change which causes three tall television towers to initiate upward positive lightning leaders. Fast, short duration, bidirectional/bipolar recoil leaders form on positive leader branches that become cutoff from their main channel.

Video I linked to last week was “only” 7207 fps.