Want to be a rock-skipping master?
Using high speed cameras, physicists at Brigham Young University in Utah and the Naval Undersea Warfare Center in Rhode Island have pinpointed the perfect technique for skimming stones--and it's pretty much what you would expect.
"Use flat round stones, and find a weight that allows you to put a lot of spin on them," Dr. Tadd Truscott, an assistant professor of mechanical engineering at the university and one of the researchers, told The Huffington Post in an email. "Throw them hard with a lot of linear and angular momentum. Throw at about a 20 degree velocity angle with about a 20 degree angle of attack!"
In other words, tilt the rock at a 20 degree angle in your hand, and throw it so that it heads toward the water at a 20 degree angle (see below).
Courtesy of Tadd Truscott.
That's the key to making your stone bounce as many times as possible. If you care more about making your stone look really cool, launch it toward the water at a much higher angle and use a lot of spin, the researchers say.
"An alternative and unconventional skipping method involves imparting a great deal of backspin to a rounded stone so that it dives under the surface and then pops up and out of the water," the researchers wrote in an article describing their findings. "The technique does not yield many skips, but it is impressive nonetheless."
Now you know!
The research was published online in December in the American Institute of Physics' publication Physics Today.