Posted in Science & Nature

Stone Skipping

Stone skipping refers to the act of throwing a flat stone on a calm body of water to make it skim the surface and seemingly bounce. However, this is a technique that is hard to master and usually results in the stone simply sinking. Thus, a paper researched how one can improve their stone skipping skills.

According to the study, a stone that is 5cm in diameter, 2cm thick and about 100g in weight is ideal. But choosing your stone is only the first step.
This stone must enter the water at 20 degrees at a speed of over 90km/h to make sure the stone will skim. Furthermore, the stone needs to be lifted up about 20 degrees against the water.
Lastly, the stone needs to be spinning with enough force to drive it forwards while keeping it off the surface of the water. This is known as the gyroscope effect (the same reason why a top does not fall when spinning).

However, it is difficult calculating and throwing the perfect angle and speed unless you are a machine. Ergo, the only effective way to master the skill is through practice and effort.
A handy advice is to throw the stone as fast as possible from a low position, letting go of the stone just below your knee height-wise.

Posted in Science & Nature

Egg

To know whether an egg is raw or boiled, simply spin the egg on its side, put a finger on top of it gently to stop it, then let the finger go.

A raw egg continues to spin because of the inertia of the liquid yolk still spinning within the shell.