FRANCE BIDS FOR A NOBEL PRIZE:

Stone skimming formula adds new spin (Hazel Muir, 16 October 02, New Scientist)

Inspired by his eight-year-old son, physicist Lydéric Bocquet of Lyon University in France wanted to find out more. So he tinkered with some simple equations describing a stone bouncing on water in terms of its radius, speed and spin, and taking account of gravity and the water's drag.

The equations showed that the faster a spinning stone is travelling, the more times it will bounce. So no surprise there. To bounce at least once without sinking, Bocquet found the stone needs to be travelling at a minimum speed of about 1 kilometre per hour.

And the equations also backed his hunch that spin is important because it keeps the stone fairly flat from one bounce to the next. The spin has a gyroscopic effect, preventing the stone from tipping and falling sideways into the water.

Amelie will be so happy. Posted by Orrin Judd at October 18, 2002 5:42 PM