5.6 JUMPS, BENDS, AND LAUNCHES 96 Runners depend on friction between their shoes and the track for grip. Spikes in running shoes increase friction to prevent slipping and maximise acceleration. Sir Isaac Newton first observed the Magnus effect in 1670 while watching a spinning tennis ball curve. Angular momentum refers to the rotational motion of a body and is defined as the product of the moment of inertia and angular velocity of the body. PHYSICS IN SPORTS Sports are real-world examples of science in action, and physics plays a key role in helping athletes refine techniques to gain an advantage. Newton s three laws inertia, acceleration, and reaction for example, explain how athletes can manage their movements to enhance speed and performance, but, in general, physics helps explain various aspects of sports, from improving movement and power to optimising training, preventing injuries, boosting mental focus, and even designing aerodynamic clothing and devices. Physics in track and field sports In track and field sports, athletes use force, energy, and aerodynamics to run faster, jump higher, and throw farther. By applying physics principles, they can optimise technique and push their limits. In these types of sports, Newton s three laws of motions are involved: first law (inertia): a sprinter remains still until muscle force moves them; second law (acceleration): more force means greater acceleration (e.g. sprint start); third law (action-reaction): the runner pushes the track, and the track pushes back, moving them forward . to boost: potenziare to lean: piegarsi sideways: lateralmente to skid: scivolare spike: tacchetto 178 SCIENCE AND PHYSICS If obstacles are large, jump higher. Steve Backley Forward thrust Magnus force Physics in ball sports Even ball sports are based on physics principles and understanding these concepts helps explain how balls move, spin, and interact with players and the environment. In sports like football, basketball, tennis, and golf, a ball follows a curved path called a parabola when thrown, kicked, or hit. This motion is influenced by initial velocity, gravity, and air resistance. For example, when a ball spins, it creates a pressure difference in the surrounding air, causing it to curve. This is called the Magnus effect : when a player kicks the ball with spin, the air moves faster on one side and slower on the other. This difference in air pressure creates a force that pushes the ball sideways, making it curve instead of travelling in a straight line. Physics in wheel-based sports Wheel-based sports, such as cycling, skateboarding, motor racing, and wheelchair racing, rely on physics principles and angular momentum . In cycling, skateboarding, and racing, turning requires centripetal force, provided by friction, and leaning into the curve. Without enough force, the rider skids outward due to inertia. Wheels spin when force is applied, and their movement helps keep them stable. In cycling and racing, faster-spinning wheels help riders stay balanced and in control.