The tendency for an object to follow a curved path instead of a straight one is known as the magnus effect

As the rotating object moves through the air, it pushes the air on side of the ball whilst disturbing and slowing the flow on the other side down. What this does is, it creates a pressure differential. Faster moving air exerts lesser pressure and slower moving turbulent air exerts a higher pressure. And as a result, the ball experiences a force ( known as the magnus force ).

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