Physics Special Topics

Highlights of Physics Special Topics Vol.12

Volume 12 (2013/14) of the University of Leicester Journal of Physics Special Topics is now complete. This year, six groups of students published 64 short papers covering a wide range of subjects - from extreme altitude wind power, to orbits around black holes.

Take a look below to see the 6 papers that the students themselves selected as this years highlights.

Or read about the educational purpose of the Journal.

PST in the media

 

Shields Up! The Physics of Star Wars

Joseph McGuire, Alexander Toohie, Alexandra Pohl

Science says Star-Wars style laser deflectors can be made - but would they be worth the trouble?

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A group of physics students from the University of Leicester have found that the deflector shields seen in Star Wars are not only within the realms of reality, but they could also be constructed using today’s technology. Inspired by the recent announcement of Star Wars Episode VII, Joe McGuire, Alexander Toohie and Alexandra Pohl set out to explore the physics of shields in the Star Wars universe.

They made some simple assumptions based on watching the current Star Wars movies, namely that the laser weapons used just red or green light, and the deflector shields used plasma held in place by a powerful magnetic field.

Plasma is the fourth state of matter, and consists of a very hot gas of ions and electrons. The magnetic field acts similarly to the Earth’s, preventing the plasma from leaking into space.

This plasma deflects the laser beams via a process called “surface plasmon resonance”, in which the particles within the plasma oscillate (bounce back and forth like a spring) at the same frequency as the light from the laser beam.

Lead author, Joe McGuire says “this is a fascinating result, and could even be used to shield planes and vehicles, not just spaceships!”

The group show that the shields would be effective at blocking the laser weapons, and would also block all visible light. This would mean that the pilots wouldn’t be able to simply look out of a window to see.

One of the authors Alexander Toohie says “This shouldn’t be a problem. Ultra-violet cameras are used all the time these days - there should be no reason why they couldn’t use a similar camera to see with.”

The group expect that in the future we may well be using these sorts of shields as laser technology becomes more commonly used as a weapon.

The paper can be found at: https://physics.le.ac.uk/journals/index.php/pst/article/view/678/486

 

Daredevil would have met his death had he jumped on Mars

Hannah Lerman, Benedict Irwin, Peter Hicks

mars-sky-diver.jpgUsing models designed by NASA, physics students find that daredevil Felix Baumgartner would need to jump from a greater height if he repeated his record breaking jump on Mars.

On October 14th 2012 Felix Baumgartner broke three world records at once when he jumped from 19.5 miles above the Earth’s surface. Physics students from the University of Leicester have investigated how Felix’s fall would have been different on the Red Planet.

Felix’s descent was limited on Earth by his terminal velocity, the maximum speed at which anything could fall in Earth’s atmosphere. This velocity occurs when the force due to gravity matches the resistances from the atmosphere.

Starting from the same height under Mars’ gravity and the atmosphere calculated by NASA’s model, the students proved that Felix can go even faster than on Earth. The atmosphere is thinner on Mars meaning there is less air resistance holding him back from obtaining more records.

On Mars his terminal velocity, the fastest speed he will reach, would be 1000 miles per hour. The students calculated that he would get to that speed only 700m above the ground, roughly the height of the second tallest building on Earth, the Shanghai Tower. Pulling the parachute at these kind of heights is a risky business when travelling so fast. Therefore, the students concluded that Felix would need to jump from even higher to still survive.

The paper can be found at: https://physics.le.ac.uk/journals/index.php/pst/article/view/655/450

 

The power of lightning: an untapped energy source?

Magdalena Szczykulska, Jason John Watson, Lilian Garratt-Smithson, Alistair William Muir

lightning.jpgLightning has always fascinated people due to its visual beauty, unpredictability and associated power. The paper ‘Using the Forks: The Energy Yield of a Lightning Bolt’ quantifies the power carried by a single bolt of lightning and investigates lightning as a viable energy source in the future.

The analysis of the equations, published in the Journal Special Topics on 17 October 2013, indicates that 50 lightning bolts produce the same amount of energy as a single wind turbine in one year. As suggested by J. E. Oliver in ‘Encyclopaedia of world climatology’, lightning strikes 40 times a second worldwide. A co-author of this paper, Alistair Muir, said: “If we could harness just 25000 of the 1.5 billion potential strikes in a year, we would produce the same amount of energy as a small wind farm in the same period”.

With the rising utility bills, energy is becoming an important issue in UK households. As estimated by the Office for National Statistics, the energy spending for an average UK household has increased from 28% to 36% in the period of 10 years. If a new energy source can be found with low production expenses, this could act to dramatically reduce these energy costs.

Contrary to popular belief, lightning current travels upwards and downwards several times in one strike. According to Muir: "If efficient methods can be developed to harness sufficient quantities of lightning, this could help to solve the energy crisis problem. It is hoped that further research into the phenomenon of lightning will enable the development of such technology."

“Our paper only considers the energy yield from the downward currents, but the upward currents carry much greater quantities. If the upward currents could somehow be harnessed too, this would significantly increase the potential energy yield from a lightning bolt.” The upward currents can be seen in the following YouTube video: http://www.youtube.com/watch?v=JVXy-ZqqZ-g.

If efficient methods can be developed to harness sufficient quantities of lightning, this could help to solve the energy crisis problem. It is hoped that further research into the phenomenon of lightning will enable the development of such technology.

The paper can be found at: https://physics.le.ac.uk/journals/index.php/pst/article/view/635/429

 

Physicists discover a way to become invisible to speed cameras

Daniel Worthy, Robert Garner, Jenny Gregory, Jessica Taylor-Ashley

Physicists at the University of Leicester have calculated that if you travel fast enough, you’ll appear invisible to speed cameras!

speed-camera.jpgTaking advantage of a strange physical effect known as the Doppler Effect, scientists discovered that beyond a speed of 119 million miles per hour a number plate will become invisible.

The Doppler Effect means says that if something is travelling really fast its colour will appear to change. The faster it goes, the more its colour changes. If you can travel fast enough, then the colour will change so much that it will no longer be within the visible range of colours. At this speed it will only appear in the infra-red spectrum, the same type of light that night vision goggles use.

Speed cameras will not be able to see this colour, making your car will become invisible to the camera!

However, before readers go out speeding down the motorway trying to trick the cameras, this speed can’t be reached in a car. This speed is a sixth of the speed of light – a speed that only tiny particles can reach.

The fastest man-made object is the Helios probe. This is a satellite that travels around the sun. It’s speed is about a thousand times slower than the speed needed to become invisible.

Lead author, Daniel Worthy, said “It would be great fun if we could become invisible! But unfortunately our current technology isn’t advanced enough to do this.”

He added, “I would like to think that in the future, when we can travel between stars, that intergalactic speed cameras would need to look for invisible spaceships too!”.

The paper can be found at: https://physics.le.ac.uk/journals/index.php/pst/article/view/681/460

 

There’s Noah more room!

Oliver Youle, Katie Raymer, Benjamin Jordan, Thomas Morris

Noah’s Ark has long been considered by many to be merely a story; however it has recently been shown by physics students at the University of Leicester that such a vessel may have been possible!

“Luckily God provided us with exact dimensions for the ark, so after that it was just a question of calculating buoyancy!” Oliver Youle.

noahs-ark.pngUsing the dimensions stipulated in the book of Genesis, 300 by 50 by 30 cubits (a cubit is the length from your elbow to the tip of your fingers), the buoyancy could be calculated.  From this buoyancy, the maximum mass of the animals on board could be found. This turned out to be 50.5 million kilograms, the equivalent to 2.15 million sheep or 6350 double decker buses! This is about a tenth of the weight of the largest cargo ships can carry today.

Noah was asked by the Lord to take two animals of each species on his Ark. The current estimate for the number of species on Earth is 1.5 million. The paper used sheep as an average for the weight of animals, and so concluded that Noah would have unfortunately had to leave some species behind.

The physicists do not go into details about the logistics of building such a large boat out of wood, but do suggest that such a feat would be unlikely.

The paper can be found at: https://physics.le.ac.uk/journals/index.php/pst/article/view/676/475

 

What if the Moon was made of Wensleydale cheese?

Emma Longstaff, Chak Fong Edward Li, Mark Fletcher, Oliver East

A group of fourth year University of Leicester physicists, today announced their findings of what would happen if the Moon was made out of Wensleydale cheese, as in the stop animation film of Wallace & Gromit, "A Grand Day Out".

moon-made-of-cheese.pngTo find out what would happen to the Moon, the density of cheese was needed. A study of cheeses was carried out to find a range in cheese densities. To weigh the same, with a lower density, the Moon must increase in size. The cheesy Moon would appear larger in the sky because the density of the Moon is far higher than that of Wensleydale cheese. Results found that if the Moon weighed the same but was made from the tasty cheese, as seen in the Wallace & Gromit film, the Moon would look nearly 144% bigger in the night sky. Cheddar and Swiss were also used to replace the moon. It was found that a Cheddar moon would appear 148% larger in the night sky and a Swiss moon would appear 150% bigger in the night sky. On average a cheesy moon would appear one and a half times larger than it currently does (image: left).

If the Moon instead stayed the same size when changed to Wensleydale cheese the Moon would apply less force of gravity on the Earth. This would mean that the tides would be weaker, as it is the Moon that causes the daily tides.

The paper can be found at: https://physics.le.ac.uk/journals/index.php/pst/article/view/623/422

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