The ponytail

Did you hear about the groundbreaking, earth-shattering scientific discovery? Last week physicists from the University of Cambridge and the University of Warwick provided insight into Rhema’s trademark, gravity-defying, lint-collecting, twig-sporting, spaghetti sauce wearing, curly-Q hairstyle.

Yes, the Ponytail Shape Equation has been unveiled.

This equation uses a ratio known as the Rapunzel Number, which calculates the effects of gravity on hair relative to its length. Also considered in the formula are the “stiffness of individual hairs” and the average waviness and springiness of human hair.

Springiness.

Based on this data, experts can predict whether a ponytail will be pointed or fan-like. (!!!)

The research also examined how the hair swells  based on collisions between the component hairs.

“As gravity pulls a bundle of hair downward, collisions between the individual hairs cause the tail to swell outward… and the curlier the hair, the more internal collisions and thus the greater the “swelling pressure.“

Sniff. A diagnosis. Swelling pressure.

If your Rapunzel number is low, then your ponytail will fan out, ‘like a paintbrush.’ If it’s larger, you’ll likely see ’a characteristic arc that straightens out near the bottom.’

Here, we have a case of a negative Rapunzel number:

Brushing these amazing tangled locks is no small task, only accomplished with the aid of two popsicles, one in each hand. A mere five minutes later she looks like she stepped into a wind tunnel.

The “fourth order non-linear differential equation,” as study co-author Robin Ball, a physicist at the University of Warwick, described the ponytail formula, “is a three-way balance of bending, gravity and curliness.”

Now it all makes sense.