A spinning cricket ball swings in flight because
- A. gravity acts sideways on a spinning body
- B. the spin makes the ball lighter
- C. air moves faster on one side of the ball, creating a pressure difference across it
- D. the ball changes shape in the air
Explanation
The spinning surface drags air round with it, so the airflow is faster on one side and slower on the other, and by Bernoulli's principle the resulting pressure difference pushes the ball sideways. This sideways force on a spinning body is the Magnus effect, and it is why a swing bowler polishes one side of the ball. The same physics curves a football and lifts a golf ball.