One of nature’s most beautiful spectacles is simply the way a watery surface dances when a falling stone hits it, especially in the first instants after the strike. But physicists aren’t entirely clear how this process unfolds.
If one drops a pebble into a pond, a very rapid, thin plume of water spouts upwards.As the object enters the water, a tube-shaped air cavity forms behind it, the investigators noted. Moments later, the water closes in on the cavity and fills it again, but in the process, the water squeezes some of itself upward. It’s like toothpaste being squeezed out of a tube, according to the researchers.
Incidentally, they added, a second jet is also formed and forced downward, deeper into the liquid, at the same time. This second jet isn’t visible from above.When the cavity collapses, the first point of closure is at its middle.
The continued closing of the air cavity is necessary to provide the necessary force. It’s like the difference between squeezing a toothpaste tube once and squeezing it in a continuous motion toward the nozzle, very quickly