'Rapunzel number' lets scientists predict shape of any ponytail - solving a problem posed by Leonardo da Vinci

Mathematicians may have come up with a 'Rapunzel Number' that can predict the shape of any ponytail - solving a problem that has perplexed hairdressers since Leonardo da Vinci posed it 500 years ago.  


The equation, which balances gravity versus the 'springiness' of hair to predict whether ponytails will be fan-like or pointed, was 'surprisingly simple', say the researchers. 


The researchers found the number by photographing large bundles of human hair and analysing the maths


The researchers from the University of Cambridge said they had devised a 'Ponytail Shape Equation', which when calculated using the Rapunzel Number and a measure of the curliness of hair can be used to predict the shape of any ponytail.         Full Read