fluid dynamics

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The mechanical consequences of moving a body through a fluid medium—air or water in the case of sport. The primary effects relevant to sport include drag (force acting against the direction of motion), lift (force acting at right angles to the drag), and the Magnus effect (curved flight of a projectile as a result of spin). Important to the magnitude of these effects is the density of the fluid (water is about 820 times as dense as air) and the speed of movement. In most sports, most of the time, the effects produced may be effectively ignored because they are so small, or affect all competitors equally. For example, the mechanical consequences of air as the medium during walking or a shot-put are negligible. But in aquatic sports, fast-moving sports, and many ball sports, the effects are large and techniques to minimize or maximize the effects are an inherent part of the sport. Examples include swimming costumes to aid buoyancy and reduce drag, or drafting in cycling to reduce drag, or spinning a football to produce swerve or dip.

Subjects: Sport and Leisure.

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