The Magnus effect

During the execution and follow through stages of the basketball jump shot, players apply backspin to the ball by flicking their wrist and using their fingertips to apply spin to the underside of the ball. The added backspin increases the chance of the ball bouncing in off the backboard as the spin makes the ball bounce downwards when striking off a vertical surface. The backspin also has a significant effect on the balls flight path as the spin generates downward force that allows the ball to fall through the net more easily. This can be explained by examining the Magnus effect which is a phenomenon used to describe the effect of air pressure on spinning spherical objects. When the basketball starts spinning backwards there is a boundary layer of air that is spinning in the same direction as the ball. As the ball travels through the air this boundary layer comes into contact with air particles traveling in the opposite direction. As the bill is spinning the oncoming air on one side of the ball is moving in the same direction as the boundary layer while on the other side the air is moving in the opposite direction which creates a pressure differential (Blazevich, 2013).

                                                                   (Blazevich, 2013)

As the basketball is released from the players hand the upward velocity generates a pressure differential which pushes the ball upward and back towards the player but as gravity overcomes the force applied on the ball and it starts to fall, the Magnus effect will push the ball downward and away from the player towards the basket. This added downward force is desirable as the ball needs to travel downwards to fall through the basket. The backspin will increase the chance of the ball falling straight through the basket and decrease the chance of a defender blocking the ball.