Have you ever wondered why a spinning ball curves after being thrown? This is due to a sidewise force, called the Magnus effect (named after the German physicist and chemist H.G. Magnus, who first investigated this effect). The Magnus effect explains why the paths of these spinning balls deviate from normal flight paths.
A spinning ball deviates from the normal flight path due to the difference in pressure developed in the fluid. When a ball is spinning, the ball will drag some of the air molecules with it. The drag of the side of the ball when it is spinning against the airflow (the surface is moving in the same direction as the ball’s travel) retards the airflow. On the other hand, the other side (the surface is moving against the direction of the ball’s travel) speeds up the airflow.
Bernoulli’s principle states that as the speed of a moving fluid increases (liquid or gas), the pressure within the fluid decreases. Therefore, one side of the ball speeds up the airflow and causes low pressure, whereas the other side causes high pressure. The pressure differential creates a force which is what makes the ball deviate from the normal flight path.
Next time you throw a ball, think about the Magnus effect and how it makes the ball follow that curved path.
Works Cited
Admin (2017). Bernoulli’s Principle & Bernoulli Equation - Definition, Derivation, Principle of Continuity, Application. [online] BYJUS. Available at: https://byjus.com/physics/bernoullis-principle/. [Accessed 2 Jul. 2024].
Magnus effect | Definition, Examples, & Facts | Britannica. (2024). In: Encyclopædia Britannica. [online] Available at: https://www.britannica.com/science/Magnus-effect [Accessed 2 Jul. 2024].
Walden, M. (2021). Spin & The Magnus Effect – TeachPE.com. [online] Teachpe.com. Available at: https://www.teachpe.com/biomechanics/fluid-mechanics/spin [Accessed 2 Jul. 2024].
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