The science of swing

The swinging ball was a vital component of this summer’s ashes success. Matt Carré explains the engineering principles behind

’s secret weapon.

England cricket fans (including myself) are recovering from the euphoria of winning back the Ashes from Australia. The fantastic batting exploits of Kevin Pietersen, Shane Warne’s mesmerising spin bowling and the all-round heroics of Andrew ‘Freddie’ Flintoff are still fresh in everyone’s minds. But an equally important ingredient in this drama was the ‘swing’ and ‘reverse swing’ bowling unleashed by Hoggard, Jones, and Flintoff.

The phenomenon of ‘swing’ has been discussed at length in many scientific articles, perhaps most notably by an American friend of mine, Dr Rabi Mehta, to whom I owe much of this explanation.

A cricket ball differs from many sports balls due to the asymmetry caused by a proud seam and the fact that the fielding players keep one side of the ball smooth, whilst the other side is allowed to become rough. Any projectile that is non-symmetrical has the potential to experience some force, or combination of forces, perpendicular to its flight. An obvious example of this is the aircraft wing. Therefore it isn’t that surprising that a cricket ball, when bowled correctly, does ‘strange things’.