Researchers at Yamagata University in Japan are using finite-element analysis to simulate how people kick footballs. This illustration shows the deformation on a leg and ball, ranging from pink (the lowest) through blue, green and yellow to red (the highest). These studies have confirmed what most footballers know. If you kick the ball slightly off-centre with the front of your foot – and with your ankle bent into the shape of an “L” – the ball will curve in flight. This causes the applied force to act as a torque, which gives the ball a spin, enabling the Magnus effect to come into play.
First published in Physics World magazine, June 1998 pp25–27. https://physicsworld.com/a/the-physics-of-football/