Midland physicists have come up with an equation that explains and predicts the shape of a ponytail.

The new equation - dreamed up by scientists from Warwick and Cambridge Universities - takes into account gravity, random curls and the stiffness of hairs.

Prof Raymond Goldstein, who is the Schlumberger Professor of Complex Physical Systems at Cambridge University, said the findings showed how physics could be used to “solve a problem that has puzzled scientists and artists ever since Leonardo da Vinci remarked on the fluid-like streamlines of hair in his notebooks 500 years ago”.

“It’s a remarkably simple equation,” he said.

Prof Goldstein worked on the equation with Professor Robin Ball from the University of Warwick and Patrick Warren, from Unilever’s Research and Development Centre.

The Ponytail Shape Equation represents the first scientific understanding of the distribution of hairs in a ponytail, say the researchers.

It provides new understanding of how a bundle is swelled by the outward pressure which arises from collisions between the component hairs.

Together with a new mathematical quantity known as the Rapunzel Number, the equation can be used to predict the shape of any ponytail and opens the way to a better understanding of materials made up of random fibres.

This will resonate with some in the computer graphics and animation industry, where a realistic representation of hair and fur has proven a tough challenge.

The research is published in Physical Review Letters journal.