Is the art of spin bowling all in the cross-wind? Ahead of the Ashes, England and Australia could learn from these two physicists

Equations that govern the trajectory of a
spinning ball as it moves through the air have been published

How can a spin bowler improve his googly or doosra, his leg break or slider? Cricketers may well spend years honing their techniques to improve the flight, pitch and bounce of the ball but a pair of Australian physicists has discovered that by just waiting a few moments for a cross-wind to pick up could prove crucial to taking wickets.

Brothers Garry and Ian Robinson publish equations today that govern the trajectory of a spinning ball as it moves through the air in a swirling wind. England and Australia’s Ashes squads may want to pay attention to the paper as they seek to gain an advantage in the series, which begins at Trent Bridge, Nottingham, next Wednesday.

The brothers reveal that the presence of a cross-wind from either side of the cricket pitch can cause the spinning ball to either slightly ‘hold up’ or ‘dip’, depending on which direction the wind comes from and which way the ball is spinning. This will significantly change the point at which the ball pitches on the wicket leaving a batsman bamboozled.

The Robinsons showed that when a 14 km/h cross-wind interacts with the spinning ball, the point at which it hits the ground can change by around 14 cm, which they believe may be enough to further deceive an opponent.

Other factors they took into account were the speed of the ball, gravity, the drag force caused by air resistance and the Magnus or ‘lift’ force, while at the same time incorporating the important effect of wind.

The Magnus force is a common effect, particularly in ball sports, when the spin of a ball causes it to curve away from its set path. Wrist spinners like Shane Warne especially utilise the effect to get the ball spinning as fast as possible. The effect on a topspin delivery makes the ball dip faster in the air and bounce further away from the batsman than he originally thought it would. The extra dip also means that the ball will hit the ground at a steeper angle and therefore bounce higher.

Isaac Newton first correctly observed and inferred the Magnus effect when watching tennis players at Trinity College, Cambridge. The effect itself is named after German physicist Heinrich Gustav Magnus who described it in an 1852 paper while investigating how to make German artillery more accurate.

Footballers such as David Beckham also utilise the effect when curling the ball around defenders or a wall of players from a set piece.

Garry Robinson said: “Our results show that the effects on a spinning ball are not purely due to the wind holding the ball up, since a reversal of wind direction can cause the ball to dip instead. These trajectory changes are due to the combination of the wind and the spin of the ball.

“The effects of spin in the presence of a cross-wind, and how to fully exploit it, may or may not be completely appreciated by spin bowlers. Either way, we have provided a mathematical model for the situation, although the model of course awaits detailed comparison with observations.”

Once the equations were constructed, they were solved using a computer software program: the solutions were then used to create illustrative examples for cricket.
The Robinsons, from the University of New South Wales and the University of Melbourne, also showed that a spinning cricket ball tends to ‘drift’ in the latter stages of its flight as it descends, moving further to the off-side for an off-spinning delivery, which Graeme Swann specialises, and moving further towards the leg-side for a leg-spinning delivery. Their research is published in the Institute of Physics’s Physica Scripta journal.
Garry added: “We hope that this work can be used to cast new light on the motion of a spinning spherical object, particularly as applied to cricket, whilst also stirring the interests of students studying differential equations.”

Have you tried new the Independent Digital Edition apps?
Caption competition
Caption competition
Latest stories from i100
Daily Quiz
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

Career Services

Day In a Page

Blundering Tony Blair quits as Middle East peace envoy – only Israel will miss him

Blundering Blair quits as Middle East peace envoy – only Israel will miss him

For Arabs – and for Britons who lost their loved ones in his shambolic war in Iraq – his appointment was an insult, says Robert Fisk
Fifa corruption arrests: All hail the Feds for riding to football's rescue

Fifa corruption arrests

All hail the Feds for riding to football's rescue, says Ian Herbert
Isis in Syria: The Kurdish enclave still resisting the tyranny of President Assad and militant fighters

The Kurdish enclave still resisting the tyranny of Assad and Isis

In Syrian Kurdish cantons along the Turkish border, the progressive aims of the 2011 uprising are being enacted despite the war. Patrick Cockburn returns to Amuda
How I survived Cambodia's Killing Fields: Acclaimed surgeon SreyRam Kuy celebrates her mother's determination to escape the US

How I survived Cambodia's Killing Fields

Acclaimed surgeon SreyRam Kuy celebrates her mother's determination to escape to the US
Stephen Mangan interview: From posh buffoon to pregnant dad, the actor has quite a range

How Stephen Mangan got his range

Posh buffoon, hapless writer, pregnant dad - Mangan is certainly a versatile actor
The ZX Spectrum has been crowd-funded back into play - with some 21st-century tweaks

The ZX Spectrum is back

The ZX Spectrum was the original - and for some players, still the best. David Crookes meets the fans who've kept the games' flames lit
Grace of Monaco film panned: even the screenwriter pours scorn on biopic starring Nicole Kidman

Even the screenwriter pours scorn on Grace of Monaco biopic

The critics had a field day after last year's premiere, but the savaging goes on
Menstrual Hygiene Day: The strange ideas people used to believe about periods

Menstrual Hygiene Day: The strange ideas people once had about periods

If one was missed, vomiting blood was seen as a viable alternative
The best work perks: From free travel cards to making dreams come true (really)

The quirks of work perks

From free travel cards to making dreams come true (really)
Is bridge the latest twee pastime to get hip?

Is bridge becoming hip?

The number of young players has trebled in the past year. Gillian Orr discovers if this old game has new tricks
Long author-lists on research papers are threatening the academic work system

The rise of 'hyperauthorship'

Now that academic papers are written by thousands (yes, thousands) of contributors, it's getting hard to tell workers from shirkers
The rise of Lego Clubs: How toys are helping children struggling with social interaction to build better relationships

The rise of Lego Clubs

How toys are helping children struggling with social interaction to build better relationships
5 best running glasses

On your marks: 5 best running glasses

Whether you’re pounding pavements, parks or hill passes, keep your eyes protected in all weathers
Joe Root: 'Ben Stokes gives everything – he’s rubbing off on us all'

'Ben Stokes gives everything – he’s rubbing off on us all'

Joe Root says the England dressing room is a happy place again – and Stokes is the catalyst
Raif Badawi: Wife pleads for fresh EU help as Saudi blogger's health worsens

Please save my husband

As the health of blogger Raif Badawi worsens in prison, his wife urges EU governments to put pressure on the Saudi Arabian royal family to allow her husband to join his family in Canada