Physicists have found why the untied shoelaces
Physics with a high-speed shooting found out that the cause of the outbreak of the laces is the changing of force during the movement of the legs. A major role in the outcome of the work took the inertia forces that are pulling loose ends of the laces in rapid movement of the foot, and the reaction to the hitting surface.
A study published in the journal Proceedings of the Royal Society A. a Brief statement posted on the website EurekAlert!
If you look with laces, you can tell a lot about DNA and other systems, decaying under the action of dynamic forces,”Christopher Daley-Diamondcounter work from the University of California at Berkeley.
The aim of the study was to understand the mechanics of the process of unleashing a node of a bow on the laces under the action of dynamic forces. In previous works described how the untied knots at continuous loads, but the dynamic changes of forces and loads has received little attention. Scientists have found that the force developed upon impact on the surface, seven times larger than the gravitational force. The node is stretched and attenuated in response to the impact. Then rising with an acceleration of the foot causes the forces of inertia, nagging loose ends that can quickly untie the loose knot.
In addition to the dynamic interaction of forces on the node high-speed imaging also showed a large value of acceleration at the base of the node.
“We need a pulse force at the base of the knot, and twisting the free ends and petesch, explains the daily diamond. — Apparently, the node is not undone without both component.” The authors tested their findings by increasing the weight of the ends, and the knot began to come loose much faster.