Silly Science: The Physics of Bumps in Rugs
{{#rendered}} {{/rendered}}Work done in the name of science is earnest, educational, and occasionally downright dumb.
A paper published in the current issue of Physical Review Letters describes research done on the author's bathroom rug. The author investigated everything about wrinkles in rugs — known also as rucks — including how they form, how they move, and what happens when they interact.
Bumps in bathmats?
{{#rendered}} {{/rendered}}"It's always used as an analogy for lots of things in physics," said Physicist Dominic Vella from the University of Cambridge in the United Kingdom, adding that in order to know for sure if these analogies are accurate, "you have to first understand the physics of the ruck in the rug."
Confirming analogies is fine in your free time, but Vella's work was nurtured and encouraged by a generous grant from The Royal Commission for the Exhibition of 1851, an educational trust that supports research in science and engineering in England. And the Royal Commission is run by the Duke of Edinburgh. In other words, his royal highness Prince Philip gave Vella money to study his bathmat.
To be fair, the team's works is quite interesting. Vella’s team studied the form that bumps take, how well they hold that shape and how fast they move across a flat surface. First, Vella and his team tested rubber mats of different thicknesses on a variety of flat surfaces. After observing how a wrinkle in the rubber mat developed on wood, sandpaper and metal, the team compared it to the behavior of Vella's own bathroom rug on the same surfaces. To see how these wrinkles move, the team used a high-speed camera to film the mats while a team member waved one end up and down.
{{#rendered}} {{/rendered}}They found that larger wrinkles have an easier time supporting themselves no matter what kind of surface the rug sits on. Smaller bumps smooth out quickly unless there's a lot of friction holding them up from the surface below. For most types of carpet Vella tested, moving bumps travel at around one meter per second, though smaller ones tend to move faster than larger ones. When two wrinkles collide, they combine to form a bigger one that moves even faster.
A second paper in the same journal expands upon this work. Mathematics professor L. Mahadevan of Harvard's Applied Math Lab looked at how gravity pulls a bump down a ramp. He placed a wrinkled rubber sheet on the bookshelf borrowed from his office and tilted it until the wrinkle started rolling on its own. He describes in detail the bump's speed, shape, and angles at which different sizes started rolling.
Analogies that make complex topics accessible is certainly smart. But if oversimplified, the most elaborate research can come off as ... just a little silly.
{{#rendered}} {{/rendered}}Inside Science News Service, which is supported by the American Institute of Physics, a not-for-profit publisher of scientific journals, contributed to this story.