Wednesday, November 9, 2016
Noncoalescence of Drops - dancing water on water
Drops of water sometimes bounce off a pool of water instead of coalescing. Fluid dynamicists have been fascinated by this behavior since the 1800s, but it was Couder et al. who explained that these droplets can bounce indefinitely as long as the thin air layer separating the drop and pool is refreshed by vibrating the pool.
In this video, Destin from SmarterEveryDay teams up with astronaut Don Pettit to film the phenomenon in beautiful high-speed.
It turns out that the cello produces just the right frequencies to create a cascade of bouncing water droplets.
And since Destin mentions the equation of Collisional Kinetic Energy (CKE), I have to mention that a perfectly elastic collision is defined as one in which there is no loss of kinetic energy in the collision. An inelastic collision is one in which part of the kinetic energy is changed to some other form of energy in the collision.