First thing first. No, this isn’t a Ronaldo vs Messi debate. So football fans, hakuna your tatas.
We have all seen players hit a ball that swerves and curls in the air. Find below one of the best curling free-kicks of all time. What a beauty! What a footballer requires to achieve such a feat is hours and hours of practice. And the Magnus Effect!
When the ball is kicked and it travels ahead, the air flows from the front of the ball towards the back. This creates a drag — friction of air molecules on the surface of the ball. The footballer also gives the ball a spin by hitting it slightly off centre. This spin means that one side of the ball is spinning in the same direction as the airflow, whereas the other side is spinning in the opposite direction of the airflow. This imbalance is the key to the Magnus effect.
The side that is spinning in the direction of the airflow (left side in the figure) has lesser drag (friction) than the side that is spinning against the airflow. This lesser drag means that that the air moves faster on the left side. Bernoulli’s principle tells us that an increase in speed of the fluid (air) must always be accompanied by a decrease in pressure. This means that the left side of the ball has a lower pressure and the right side has a higher pressure. Air flows from a region of low pressure to high pressure. This property of air pushes the ball towards the left, thus giving the kick a curl!
Similarly, the Magnus Effect is used to curl the ball in other sports like Tennis and Baseball.
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From the desk of Aditya Khanduri
About me (Why I started Polygyan)
