EducationalGifs

"When you touch it, it explodes"

Nitrogen Triiodide is an extremely sensitive explosive compound that, when dry, can be detonated by the lightest of touches or vibrations. 

Click here for the full video.

Adding two identical waves, shifted by different amounts, to give a new wave. The waves interfere to either amplify each other, cancel each other out, or something in between. [more] [code]

From The Physics Girl: “What happens when you drop a perfectly balanced stack of balls? And how is the result like a supernova? The classic momentum transfer demonstration, at the next level.”

Watch the video (and then try it).

With a tail that can be long as its body, the Thresher Shark attacks its prey with violent whip like motions.

This behaviour has been suspected by researchers, but only recently has it been caught on film. The tail is used to stun, maim or even kill the prey, with the shock-wave created by the momentum also stunning surrounding fish.

It is thought to be an evolutionary adaptation as these sharks hunt mainly smaller fish such as sardines. This makes the whip mechanism much more efficient at catching multiple fish with a single blow, as opposed to one fish at a time the shark would tend to catch with its jaws.

The tail was caught moving at up to 80 km/h, spontaneously heating and even boiling small areas of water near the very tip of the tail due to the extreme forces involved. 

Sepios

Inspired by the cuttlefish these students at the Swiss Federal Institute of Technology built a nautical robot that mimics the locomotion.

“The only four finned cuttlefish robot in the world, Sepios distances itself from classical nautical vehicles with its omnidirecitonality and high maneuverability. These qualities combined with its fishlike appearance and low disturbance are ideal for closing in on fish, making it the ideal device for marine life filming.”

Hummingbirds can beat their wings up to 80 times a second during normal flight and up to 200 times per second during a courtship dive. They are the only bird that can fly forwards, backwards, up, down ,sideways and  hover in mid air. 

Sometimes, against a uniform, bright background such as a clear sky or a blank computer screen, you might see things floating across your field of vision. These “floaters” are not any kind of external objects, nor are they alive. Rather, floaters are tiny objects that exist inside the eyeball, and cast shadows on the retina - the light-sensitive tissue at the back of your eye.

To learn more about floaters, watch the TED-Ed Lesson What are those floaty things in your eye? - Michael Mauser

Animation by Reflective Films

Phototubes, shown here, emit electrons when exposed to light that produce electrical currents. This 1937 episode of GE’s “Excursions in Science” series came out just as manufacturers were beginning to take the device mainstream. The first commercial application was the reproduction of sound for motion picture films.