Why are the laces untied?

Although a lot of research has been done on the durability of different knot structures, there has been no study on how a knot can untie itself. Until an academician wondered why his little girl's shoelaces were constantly untied. Then, together with his two students, he closely observed what effects shoelaces were exposed during the run.

Under normal conditions, a knot you put on your shoelaces remains as it is thanks to the friction in the center, and the more the loops are entangled, the stronger the knot, because every bond formed increases friction.

However, suddenly hitting the foot on the ground during the run disrupts all the work. This multiplication causes a force to be applied to the center of the knot and creates an acceleration. This momentum pulls the laces on both sides, as if the laces move back and forth at each step, as if it were an invisible hand. In the end, there comes a moment when the acceleration overcomes the friction and the knot suddenly unties.