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Drag forces and spin

Horizontal curve in soccer ball trajectory.


When a soccer ball is shot under an angle up into the air, then, under the influence of gravity, we expect it to follow approximately a parabolic trajectory. However, the video shows a very different trajectory. Namely the ball's trajectory is curved in the horizontal direction. This cannot be an effect of gravity, because gravity acts in the vertical direction. Hence, something else is at stake. It actually is one more effect of air resistance which is known under the name of Bernoulli's principle.

Here we will study this phenomenon.


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