Magnus Effect (Curve path by spinning ball).

Magnus effect

The Magnus effect is the commonly observed effect in which a spinning ball curves away from its principal flight path.

The Magnus effect is a lift force of tremendous importance to all athletes who want to bend the flight of a ball.

Golfers, baseball pitchers, and soccer, tennis, and table tennis players all employ this effect to curve the flight path of the ball. The game of baseball in particular is made more fascinating by the Magnus effect.

The Magnus effect operates in the following manner.

As a spinning ball moves through the air, it spins a boundary layer of air that clings to its surface as it travels along. On one side of the ball the boundary layer of air collides with air passing by. The collision causes the air to decelerate, creating a high-pressure area. On the opposing side, the boundary layer is moving in the same direction as the air passing by, so there is no collision and the air collectively moves faster. This sets up a low-pressure area. The pressure differential, high on one side and low on the other, creates a lift force (the Magnus force) that causes the ball to move in the direction of the pressure differential (i.e., from high to low).

The Magnus effect can combine with the force of gravity or fight against gravity.

The Magnus effect can be applied in any direction, and in this way an athlete can create backspin, topspin, and sidespin. Soccer players are well known for the way they use “banana kicks” (i.e., the Magnus effect) to curve free kicks and corner kicks around defenders and into the goal mouth. Tennis players and volleyball players use the Magnus effect when they apply topspin to make the ball drop suddenly while in flight.