IELTSwithJurabek

PASSAGE 2

You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2 on pages 7 and 8.

The aerofoil

The shape of an aeroplane's wing plays a key role in the achievement of flight

14A The magic of flight lies in the interaction between the wings of a plane and the air. If the shape of the wing - the aerofoil - is right and the plane is moving fast enough, the wing is pushed into the air as it slices through it. It seems like magic because our all-too-literal brains tell us that because air is invisible it must be insubstantial too. But air is not nothing; air is a substance completely comprised of gases. If you think of a wing slicing through water rather than air, you can begin to imagine how air might provide the upward push that aeronautical scientists call lift. The key to the aerofoil is the flow of air around it. Air flows around an aerofoil because the aerofoil is moving. Just as the bow of a boat creates a flow in still water, what matters is the way the curved shape of the aerofoil diverts the flow around it.

15B To really see why, it is worth carrying out an experiment with knives and spoons under a running tap. Hold the blade of a knife vertically in a stream of water and the water flows straight and undisturbed past the blade. Twist the blade slightly at an angle to the stream and you can see how it begins to block and split the flow, breaking it into turbulent eddies - and you may see the turbulence increase as you increase the angle of the knife. Hold the convex side of a spoon under the stream instead, however, and something different happens. The spoon diverts the water but does not disrupt it. You have to twist the spoon at a much steeper angle before it disrupts the flow. Like the curvature of the spoon, the curvature of the aerofoil ensures the flow of the air around it is diverted but not broken up.

16C The curvature of the spoon, like that of the aerofoil, is crucial. Far above or below the aerofoil the airflow is undisturbed, but the closer the air is to the aerofoil the more the flow is bent to follow the aerofoil's shape. As the air changes direction, it begins to push in a different direction too, and the more it bends, the greater the change. Right on top and underneath the aerofoil, the airflow is turned effectively at right angles, pushing the aerofoil upwards and creating lift. Since it is the way that the airflow is distorted that creates lift, it is evident that the pattern of the airflow distortion is critical. This depends on the angle that the aerofoil moves through the air - its angle of attack - the steeper the angle, the greater the lift.

17D The overall shape of the aerofoil is also crucial. A gentle, thin, curve - the shape that the flexible wings of hang-gliders and microlights bend into - gives the maximum lift, which is why the wings have to be so huge. This shape is hard to make a large wing strong enough in, so to make a large aircraft, the wings of most large aeroplanes are, in profile, the shape of a narrow teardrop. This shape does not give us much room for fuel storage. They are hollow inside, which can be swung up or down to alter the aerofoil curvature and its effective angle of attack and so allow the aircraft to climb or descend.

18E Of course the wings of birds were the original inspiration for the aerofoil. Countless thinkers in the distant past must have marvelled at birds gliding through the sky and guessed that they were held aloft by their outstretched wings. And perhaps it was the early Greek philosophers who are said to have built a mechanical bird that flew. Brave pioneers like the 9th-century Cordoban inventor, Abbas Ibn-firnas, were even bold enough to strap artificial wings to their arms and leap from high places. Ibn-firnas was lucky enough to glide through the air for ten minutes before crash-landing and almost breaking his neck.

19F Yet the first person who really began to explore the shape of wings methodically was the British engineer Sir George Cayley (1773-1857) and it is to Cayley that we owe the idea of the curved aerofoil. Cayley was an extraordinary and inventive man, and he is credited with developing self-righting lifeboats, wire-spoked wheels, seatbelts and even an internal combustion engine. But it is mostly as the father of aviation that he is remembered, and it is he who pioneered much of the theory of flight. He carried out experiments with different aerofoils, analysing what shapes and angles produced the greatest lift. In his analyses, he developed the names of the key forces involved in flight, lift, drag and thrust - which still play an important role today. Flight involves a balance between these four forces, but for a successful aeroplane you need both power and control, which is why it took another half-century before Orville and Wilbur Wright made their historic flight at Kittyhawk in the USA on 17th December 1903.

You should spend about 20 minutes on Questions 27-40, which are based on Reading Passage 3 below.

Looking for Inspiration

Helen Phillips asks what makes one person more creative than another.

People have speculated about their own creativity for centuries - perhaps ever since we became able to think about thinking. Whatever creativity, it is thinking that results in new ideas and new ways of doing things. The only bit of the creative process we actually know about is the moment of insight, yet creative ideas and projects may incubate beyond our awareness for months. Not surprising, then, that creativity has long eluded scientific study.

In the early 1970s, it was still seen as a type of intelligence. But when more subtle tests of IQ and creative skills were developed in the 1970s, particularly by the father of creativity testing, Paul Torrance, it became clear that the link was not so simple. Creative people are intelligent, in terms of IQ tests at least, but only averagely or just above. While it depends on the discipline, in general, having beyond a certain level IQ does not help boost creativity.

Because of the difficulty of studying the actual process, most early attempts to study creativity concentrated on personality. According to creativity specialist Mark Runco of California State University, the creative personality tends to place a high value on aesthetic qualities and have broad interests, providing lots of resources to draw on and knowledge to recombine into novel solutions. 'Creatives' have an attraction to complexity and an ability to handle conflict. They are also highly self-motivated, perhaps even a little obsessive, when it comes to realising their ambitions.

But there may be a price to pay for having a creative personality. For centuries, a link has been made between creativity and mental illness. Psychiatrist and author Kay Redfield Jamison of Johns Hopkins University, who herself has bipolar disorder, found that established artists are significantly more likely to have mood disorders. But she also suggests that a switch of mood state might be the key to triggering a creative event, rather than the negative mood itself.

Jordan Peterson, a psychologist at the University of Toronto, has carried out work that suggests that the brains of creative people are more open to incoming stimuli than less creative types. Our senses are continuously feeding a mass of data into our brains, which have to block most of it to save us from being snowed under. Peterson calls this process latent inhibition and argues that people who have less of it, and who have a reasonably high IQ, can juggle more of the data, and so may be open to more ideas.

But what of the creative act itself? One of the first studies of the creative brain at work was by Colin Martindale, a psychologist from the University of Maine. Back in 1978, he used a network of scalp electrodes to record the pattern of brain waves as people made up stories. Creativity, he showed, has two stages: inspiration and elaboration, each characterized at very different states of mind. While people were dreaming up their stories, he found their brains were surprisingly quiet. The dominant activity was alpha waves, which is the same sort of brain activity as in some stages of dreaming or rest. This could explain why sleep and relaxation can help people be creative.

However, when these quiet-minded people were asked to work on their stories, the alpha wave activity dropped off and the brain became busier, revealing increased cortical arousal, and more organised thinking. Strikingly, it was the people who showed the biggest difference in brain activity between the two stages who produced the most creative storylines. Nothing in their background brain activity marked them as creative or uncreative. 'It's as if the less creative person can't move up a gear,' says Guy Claxton, a psychologist at the University of Bristol. 'Creativity requires different kinds of thinking. Very creative people move between these states intuitively.'

Researchers are now trying to identify some of the specific anatomy of creativity. Brain studies of people with particular types of creativity show, perhaps not surprisingly, that active areas are determined by the specialist knowledge being used. Imagery, spatial awareness, language and so on - whatever the skill, it is localised to some extent to a particular brain part or parts. But it's not just these speciality areas that are active. Using information creatively needs coordination. 'Creative synthesis requires a new pattern, to put the brain in a state where many areas are simultaneously active,' says Claxton. When we concentrate in a less creative way, such as when reading the gas bill, there are fewer active centres and less synthesis.

But to be truly creative needs more than just the right personality and the right brain areas and networks. It's about using them effectively. Skills, situations and our social setting can shape our creativity just as dramatically as the brain resources we are born with. The most creative people also use the different rhythms of the day, the weekends and the holidays to help alter focus and brain state. They may spend two hours at their desk, then go for a walk, because they know that pattern works for them.

Another often forgotten aspect of creativity is social. Vera John-Steiner of the University of New Mexico says that to be really creative you need strong social networks and trusting relationships, not just active neural networks. One vital characteristic of a 'creative', she says, is that they have at least one other person in their life who doesn't think they are completely mad!