The awesome role of backspin in swing bowling and dipping yorkers: A thread.

If you've ever bowled any kind of seam in your life, you know that your fingers impart a backward spin on the ball as you release it.

Turns out, this is important in multiple ways.

First up, releasing the ball with backspin gives it rotation about its horizontal axis, much like a cycle wheel.

Much like a wheel, this enables the seam to stay upright (or slanted) without wobbling.

This is conservation of angular momentum.

This is important, because if the seam is wobbling around, it's almost impossible to get swing.

So your fingers naturally put backspin on the ball, which keeps the seam well-behaved, in a line, which is essential to even generate swing.

Turns out, this is not the only way it's important.

Remember when they talk about bowling fuller when it's swinging?

That's to give the ball more time in the air. More time = more swing = more lateral movement. Also, late swing.

Fine. But what does backspin do?

Backspin enables the ball to hang in the air for longer.

Why? Because of something called the Magnus effect.

The Magnus force is due to this backspin, and it lifts the ball.

The ball hits the ground later than it would if there were no backspin.