Following the drops dancing on a water surface, I was sent a link to drops jumping around on a super-hydrophobic surface:

A sphere is the minimum energy configuration, and this energy scales with surface/volume ratio; small spheres combining will represent a change in energy, and this energy shows up as a vibrational mode of the droplet, so it can launch itself off of the hydrophobic material. Bigger drops don’t display the behavior because the energy released is smaller in proportion to the mass that’s present.

Like so many things in science, it is probably obvious in hindsight that it has to be this way, but the real trick is thinking of looking for it ahead of time.

In an earlier post we saw other drop dynamics in microgravity that shows the vibrations when drops combine.

h/t to Tea With Buzz

What’s almost as fun as shooting things (or blowing stuff up)? Watching someone else do it in slow motion. 1 million frames per second, for 10 frikkin’ minutes

Bullets liquifying is pretty neat. Bullets getting dented with shrapnel from other impacts is pretty neat, too (can’t recall the CSI franchise using this one — yet — to prove that a particular bullet wasn’t the first one to be fired). Watching cracks in glass propagate is cool, too — it happens much faster than the bullet motion, but then, the speed of sound is the proper metric for motion in these cases (bullet speeds are of that order, and crack propagation is limited by that value), and the speed of sound is much higher is solids than in air. A million frames per second also means you can watch the bullet rotation as it passes through the field of view.