It appears seemingly out of nowhere, and leaves people wide-eyed with amazement. Long dismissed as a myth, over recent weeks it has been witnessed around the world and it could decide the outcome of today’s World Cup Final or the Wimbledon tennis championship.
Scientists call it the Magnus effect: the ability of spinning objects to create gravity-defying forces. Yet while its existence is no longer disputed, arguments still rage over exactly how to explain it.
Top sport stars, on the other hand, have only one concern: how to conjure up its powers on demand.
Some have clearly got close to mastering it. During the group stages of the World Cup, Portugal’s Cristiano Ronaldo made headlines with his stunning use of the Magnus effect to complete his hat-trick against Spain.
At first, his free kick looked far off-target, the ball seemingly headed wide of the wall of defenders. But then the force took over and magically curled the ball around the back of the wall and into the goal.
French football fans will no doubt be hoping defender Benjamin Pavard will today repeat the incredible Magnus Effect goal he scored earlier in the World Cup against Argentina. In what was arguably the shot of the tournament, he controlled a tricky cross, then struck the ball so that it first headed away from the goalkeeper, then simultaneously curled and dipped into the net.
Cynics might say Pavard was simply lucky. Yet the way he positioned his body and struck the ball suggests he knew exactly how to increase his chances of success.
The trick lies in getting the right mix of three forces: the pull of gravity, the Magnus Effect and aerodynamic drag.
The action of gravity is most familiar to us — and therefor most likely to let us down if other forces interfere with it. And that is exactly what the Magnus Effect does.
Named after German physicist Heinrich Gustav Magnus, who first investigated it in the mid-19th century, it appears whenever air flows around a spinning object, such as a football that has been kicked off-centre.
As the ball travels, its spin affects the flow of air over the nooks and crannies of its panelled surface accelerating the air travelling in the direction of the spin, and slowing it down on the opposite side.
How this makes the ball swerve has, however, long been the source of argument.
Many textbooks still claim that the change in speed causes a pressure difference across the ball, changing its direction. The argument is that the air is obeying a bit of school science called Bernoulli’s Law. This states that making fluids travel faster reduces their pressure. As the air flowing across the ball travels at different speeds, it must therefore also create a pressure difference on opposite sides of the ball, and make it swerve.
But — like so much in aerodynamics, including explaining how planes fly — the reality is more subtle.
Air is both compressible and slightly “sticky”, properties that Bernoulli’s Law struggles with. The correct explanation is actually simpler. The air travelling over the ball in the direction of the spin speeds up and changes direction. In other words, it accelerates. Then by Newton’s famous law of action and reaction, this generates a force on the ball, making it swerve.
This then leads to a simple rule: if you want the ball to curl left, then kick it to the right of centre, and vice versa.
But as Pavard’s shot showed, the Magnus effect can also make a ball dip. This requires kicking the ball slightly above-centre. That gives it top-spin, making it drop faster than gravity alone would manage. A kick below-centre gives the ball back-spin, making it travel further and flatter.
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Put like that, it sounds simple. But because the spin-rate is so important, the ball must be kicked in just the right spot. Missing by just a centimetre can send a shot from the edge of the penalty box wide of its target by a metre or more.
And on top of all this, there’s a third force to deal with: aerodynamic drag. Roughly speaking, the faster the ball, the higher the drag. But as the ball slows below around 30 km/hr, the flow of air over its surface changes, increasing the drag with sometimes dramatic effect.
The wonder is that any football player can achieve the right mix of all three forces with any reliability. Yet there’s every chance we will witness a demonstration in Moscow later today.
Tennis fans are much more likely to see the wonders of spin in today’s final at Wimbledon. That’s partly because tennis balls are aerodynamically less complex than footballs with their panelled surfaces.
But another reason is that it’s easier to control the spin-rate with a racket than a boot.
Even amateur tennis players can learn how to “slice” the ball, running their racket upward against it to produce topspin, or downward for back-spin.
The Magnus effect then does the rest. Top-spin produces a force that makes the ball drop unexpectedly fast; back-spin makes it travel further and flatter.
As a bonus, both also affect what happens when the ball hits the opponent’s racket or the ground.
Professional tennis players can summon up the Magnus Effect to order. But the top stars can also control its strength with exquisite precision.
The likes of Rafa Nadal, Kevin Anderson or Novak Djokovic can make the ball spin at over 3,500 revolutions a minute — faster than a washing-machine spin cycle.
That means the ball completes around 80 rotations when it reaches an opponent on the baseline and bends the law of gravity.
For the two teams in Moscow and the two players at Wimbledon, success or defeat could depend on their ability to wield the Magnus effect.
So whoever you support, as they prepare for the start you may want to say quietly: “may the Force be with you”.
Robert Matthews is Visiting Professor of Science at Aston University, Birmingham, UK
Champions League Last 16
Red Bull Salzburg (AUT) v Bayern Munich (GER)
Sporting Lisbon (POR) v Manchester City (ENG)
Benfica (POR) v Ajax (NED)
Chelsea (ENG) v Lille (FRA)
Atletico Madrid (ESP) v Manchester United (ENG)
Villarreal (ESP) v Juventus (ITA)
Inter Milan (ITA) v Liverpool (ENG)
Paris Saint-Germain v Real Madrid (ESP)
MATCH INFO
Tottenham Hotspur 1
Kane (50')
Newcastle United 0
Expert advice
“Join in with a group like Cycle Safe Dubai or TrainYAS, where you’ll meet like-minded people and always have support on hand.”
Stewart Howison, co-founder of Cycle Safe Dubai and owner of Revolution Cycles
“When you sweat a lot, you lose a lot of salt and other electrolytes from your body. If your electrolytes drop enough, you will be at risk of cramping. To prevent salt deficiency, simply add an electrolyte mix to your water.”
Cornelia Gloor, head of RAK Hospital’s Rehabilitation and Physiotherapy Centre
“Don’t make the mistake of thinking you can ride as fast or as far during the summer as you do in cooler weather. The heat will make you expend more energy to maintain a speed that might normally be comfortable, so pace yourself when riding during the hotter parts of the day.”
Chandrashekar Nandi, physiotherapist at Burjeel Hospital in Dubai
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%3Cp%3E%3Cstrong%3EDirector%3A%3C%2Fstrong%3E%20Omar%20Hilal%3Cbr%3E%3Cstrong%3EStars%3A%3C%2Fstrong%3E%20Muhammad%20Farrag%2C%20Bayoumi%20Fouad%2C%20Nelly%20Karim%3Cbr%3E%3Cstrong%3ERating%3A%3C%2Fstrong%3E%204%2F5%3C%2Fp%3E%0A
Name: Brendalle Belaza
From: Crossing Rubber, Philippines
Arrived in the UAE: 2007
Favourite place in Abu Dhabi: NYUAD campus
Favourite photography style: Street photography
Favourite book: Harry Potter
The UAE squad for the Asian Indoor and Martial Arts Games
The jiu-jitsu men’s team: Faisal Al Ketbi, Zayed Al Kaabi, Yahia Al Hammadi, Taleb Al Kirbi, Obaid Al Nuaimi, Omar Al Fadhli, Zayed Al Mansoori, Saeed Al Mazroui, Ibrahim Al Hosani, Mohammed Al Qubaisi, Salem Al Suwaidi, Khalfan Belhol, Saood Al Hammadi.
Women’s team: Mouza Al Shamsi, Wadeema Al Yafei, Reem Al Hashmi, Mahra Al Hanaei, Bashayer Al Matrooshi, Hessa Thani, Salwa Al Ali.
MATCH INFO
Europa League final
Who: Marseille v Atletico Madrid
Where: Parc OL, Lyon, France
When: Wednesday, 10.45pm kick off (UAE)
TV: BeIN Sports
The specs
Engine: 2.0-litre 4cyl turbo
Power: 261hp at 5,500rpm
Torque: 405Nm at 1,750-3,500rpm
Transmission: 9-speed auto
Fuel consumption: 6.9L/100km
On sale: Now
Price: From Dh117,059
Why it pays to compare
A comparison of sending Dh20,000 from the UAE using two different routes at the same time - the first direct from a UAE bank to a bank in Germany, and the second from the same UAE bank via an online platform to Germany - found key differences in cost and speed. The transfers were both initiated on January 30.
Route 1: bank transfer
The UAE bank charged Dh152.25 for the Dh20,000 transfer. On top of that, their exchange rate margin added a difference of around Dh415, compared with the mid-market rate.
Total cost: Dh567.25 - around 2.9 per cent of the total amount
Total received: €4,670.30
Route 2: online platform
The UAE bank’s charge for sending Dh20,000 to a UK dirham-denominated account was Dh2.10. The exchange rate margin cost was Dh60, plus a Dh12 fee.
Total cost: Dh74.10, around 0.4 per cent of the transaction
Total received: €4,756
The UAE bank transfer was far quicker – around two to three working days, while the online platform took around four to five days, but was considerably cheaper. In the online platform transfer, the funds were also exposed to currency risk during the period it took for them to arrive.
Sole survivors
- Cecelia Crocker was on board Northwest Airlines Flight 255 in 1987 when it crashed in Detroit, killing 154 people, including her parents and brother. The plane had hit a light pole on take off
- George Lamson Jr, from Minnesota, was on a Galaxy Airlines flight that crashed in Reno in 1985, killing 68 people. His entire seat was launched out of the plane
- Bahia Bakari, then 12, survived when a Yemenia Airways flight crashed near the Comoros in 2009, killing 152. She was found clinging to wreckage after floating in the ocean for 13 hours.
- Jim Polehinke was the co-pilot and sole survivor of a 2006 Comair flight that crashed in Lexington, Kentucky, killing 49.
Mercer, the investment consulting arm of US services company Marsh & McLennan, expects its wealth division to at least double its assets under management (AUM) in the Middle East as wealth in the region continues to grow despite economic headwinds, a company official said.
Mercer Wealth, which globally has $160 billion in AUM, plans to boost its AUM in the region to $2-$3bn in the next 2-3 years from the present $1bn, said Yasir AbuShaban, a Dubai-based principal with Mercer Wealth.
“Within the next two to three years, we are looking at reaching $2 to $3 billion as a conservative estimate and we do see an opportunity to do so,” said Mr AbuShaban.
Mercer does not directly make investments, but allocates clients’ money they have discretion to, to professional asset managers. They also provide advice to clients.
“We have buying power. We can negotiate on their (client’s) behalf with asset managers to provide them lower fees than they otherwise would have to get on their own,” he added.
Mercer Wealth’s clients include sovereign wealth funds, family offices, and insurance companies among others.
From its office in Dubai, Mercer also looks after Africa, India and Turkey, where they also see opportunity for growth.
Wealth creation in Middle East and Africa (MEA) grew 8.5 per cent to $8.1 trillion last year from $7.5tn in 2015, higher than last year’s global average of 6 per cent and the second-highest growth in a region after Asia-Pacific which grew 9.9 per cent, according to consultancy Boston Consulting Group (BCG). In the region, where wealth grew just 1.9 per cent in 2015 compared with 2014, a pickup in oil prices has helped in wealth generation.
BCG is forecasting MEA wealth will rise to $12tn by 2021, growing at an annual average of 8 per cent.
Drivers of wealth generation in the region will be split evenly between new wealth creation and growth of performance of existing assets, according to BCG.
Another general trend in the region is clients’ looking for a comprehensive approach to investing, according to Mr AbuShaban.
“Institutional investors or some of the families are seeing a slowdown in the available capital they have to invest and in that sense they are looking at optimizing the way they manage their portfolios and making sure they are not investing haphazardly and different parts of their investment are working together,” said Mr AbuShaban.
Some clients also have a higher appetite for risk, given the low interest-rate environment that does not provide enough yield for some institutional investors. These clients are keen to invest in illiquid assets, such as private equity and infrastructure.
“What we have seen is a desire for higher returns in what has been a low-return environment specifically in various fixed income or bonds,” he said.
“In this environment, we have seen a de facto increase in the risk that clients are taking in things like illiquid investments, private equity investments, infrastructure and private debt, those kind of investments were higher illiquidity results in incrementally higher returns.”
The Abu Dhabi Investment Authority, one of the largest sovereign wealth funds, said in its 2016 report that has gradually increased its exposure in direct private equity and private credit transactions, mainly in Asian markets and especially in China and India. The authority’s private equity department focused on structured equities owing to “their defensive characteristics.”
Sri Lanka's T20I squad
Thisara Perera (captain), Dilshan Munaweera, Danushka Gunathilaka, Sadeera Samarawickrama, Ashan Priyanjan, Mahela Udawatte, Dasun Shanaka, Sachith Pathirana, Vikum Sanjaya, Lahiru Gamage, Seekkuge Prasanna, Vishwa Fernando, Isuru Udana, Jeffrey Vandersay and Chathuranga de Silva.
