Physics trips up efforts to keep shoelaces tied
Mix of inertia and pavement pounding loosens knots, sends ends flying
![running screenshot](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2017/04/041117_ec_shoelace_main_free.jpg?fit=860%2C460&ssl=1)
KNOT BAD Shoelace knots don’t unravel at random. Instead, as a runner jogs, the ends of her laces swing due to inertia, and the knot deforms from the force of each footfall. Both effects cause the knot to untie.
C.A. Daily-Diamond, C.E. Gregg and O.M. O’Reilly/Proceedings of the Royal Society A 2017