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6 March 2014 1:04 pm ,
Vol. 343 ,
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
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ScienceShot: The Physics of Ponytails
12 February 2012 7:01 pm
Thinking about growing a ponytail but have no idea what it's going to look like? Ask a physicist. A new equation helps explain why some ponytails form long, thin manes, while others fan out into a cone. Average humans have about 100,000 hairs on their heads, making a hair-by-hair analysis of shape, length, and texture a daunting proposition. Instead, researchers attacked the problem with techniques from statistical mechanics, which deals with very large numbers of particles acting in a mass. They assumed that a stream of hair behaves much like a stream of fluid, and that its density decreases the further away it gets from a clip or scrunchie. When they plugged those assumptions into a formula describing the energy of a symmetrical tube of fibers, they came out with the Ponytail Shape Equation. The equation, reported 13 February in Physical Review Letters, not only explains different hair geometries, it should also help predict the dynamic behavior of bundles of fibers. In other words, when Rapunzel lets down her hair, how far it will swing.
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