Volume 10 highlights

The 2011/2012 University of Leicester Journal of Physics Special Topics is now in press - you can buy a copy for your own bookshelf for just six pounds from the Lulu print-on-demand service.

This year, we published a record 80 articles with subjects ranging from the serious The Apparent Magnitude of α Orionis Supernova to the more - shall we say - 'amusing' - Could Bruce Willis Save the World?.

It's always entertaining but, of course, the Journal also has a serious educational purpose, and all the papers that are published pass a stringent peer review process.

Below are a few of the highlights from this years offering...

David Marshall's paper on the trajectory of a falling batman goes viral!
Click here to search Google for the latest worldwide reports, watch David on CNN, or take a look at news reports on the BBC and in the Telegraph.

Read about David's experiences with the media.



Could Bruce Willis Save the Earth?

G. Brown, B. Hall, A. Back, S. Turner, Phys. Spec. Top. 10.1, 2011.

asteroid.jpgCould the Earth actually be saved from an asteroid impact by detonating a nuclear weapon in the asteroid's core?

According to Bruce Willis (Armageddon), yes!

But, sorry Bruce, Gregory Brown and co-workers show that, even the largest bomb ever built (the 50 megaton 'Big Ivan'), is almost a factor of 9 too small to save the Earth.

"Given the success of Armageddon," said Ashley Back, one of the co-authors of the paper, "we were really surprised to see just how far short Big Ivan would fall in preventing the asteroid impact."


Slamming Doors Due to Open Windows

D. Marshall, T. Hands, I. Griffiths, G. Douglas, Phys. Spec. Top. 10.1, 2011.

slamming-doors.pngHave you ever wondered why doors sometimes slam when a window is open?

In this thoughtful paper, David Marshall et. al. investigate this phenomena and attribute the effect to changes in the air flow around the door, finding that the air flow becomes significant when the door is near closing.

As David explains, "Everyone knows doors slam when windows are open, but we wondered what causes this to happen. We investigated the forces involved when closing a door with and without a window open in the room. As a door is closed, it pushes the air, creating an area of high pressure in front of the door and low pressure behind. The air then flows around the door to equalise the pressure. Pushing this air out of the way requires the person closing the door to push harder. But, if a window is open, the pressure can be equalised much more easily by exchange of air through the window. This means that the door requires less effort to close, so someone trying to push the door with the same amount of effort will accidentally slam the door."

David goes onto say, "this is easy to see in practice - I managed to annoy my housemates by trying this out for myself many times!" But the impressive part of this work was that Marshall et al managed to develop a model of this system which they could use to investigate the physics in detail.

David comments that "it's interesting to be able to explain odd behaviour that we experience on a day-to-day basis and - if you have a window open, be careful when shutting doors, or they're going to slam!"


Using High Velocity Rounds to Slow Aerial Descent

Melissa McHugh, A. West, J. Blake, R. C. Hall, Phys. Spec. Top. 10.1, 2011.

m1a1-tank.jpgThe 2010 blockbuster, The A-Team, features a scene where the legendary team find themselves falling from an exploded plane in an M1 Abrams tank. In an attempt to prevent their certain death, the A-team fire the tank's main gun downwards to try to slow their descent.

Unfortunately for Hannibal, Murdock, Face and B.A., the main gun would need to be fired an infeasible 11 times to make the impact survivable.

Melissa McHugh explains the motivation behind the work, "There are many instances in popular culture where we find ourselves wondering at how practical a concept really is. How many people have wondered what it would take to build a warp drive from star trek? In this case, the scenario with the falling tank was far simpler to analyse with the physics we already know."

"From analysing the forces involved (air resistance, gravity, and the recoil of the cannon) we found that the force from the recoil of the gun is too small to make any difference. However, the fact that the tank still had one of the original three parachutes was enough to ensure that the tanks would only impact at about 34 miles an hour."

The physics involved in this paper is highly transferable to real world problems (especially those involving falling tanks!). Melissa also comments that, "it is important for us as scientists to understand the process by which information is publicised. There is no point to a discovery if you cannot tell anyone about it. So for the most part, this paper was good practice for our future as physicists."


Mars Airport

M. Grant, A. Edgington, N. Rowe-Gurney, J. Sandhu, Phys. Spec. Top. 10.1, 2011.

mars.jpgManned missions to Mars have been the subject of a great deal of speculation. But, once humans arrive on the red planet, how would they get around?

This paper discusses the use of pre-existing aircraft and the modifications required to make them useful on Mars.

It turns out that large scale manned transport could be provided by helicopters with rotors 2x larger and 2.5x faster than their Earthly counterparts.

Amy Edington, one of the co-authors of the papers explains, "the atmospheric differences on Mars requires the dimensions of various aircraft to be modified. Using the standard equations of fluid dynamics we calculated the changes needed to adapt a Helium balloon, a helicopter, and an aeroplane for carrying out the same tasks on Mars as they do on Earth. We found that the balloon's size would have to be increased to an unreasonable size to carry even a small mass, but that a helicopter would be able to operate on Mars with a relatively small change to either the rotor size or speed compared to the increases needed for a plane."

Amy goes on to say that calculations like these are important when planning scientific missions to Mars, or even when thinking how to transport people when manned missions to the Red planet become a reality.


Trajectory of a falling batman

D. Marshall, T. Hands, I. Griffiths and G. Douglas, Phys. Spec. Top. 10.1, 2011

Marshall et al investigate how well Batman would be able to glide, given the size of his cape as seen in Batman Begins.

There is a real life example of this physics at work: see the recent helicopter jump by Gary Connery, which was completed with only a wingsuit, no parachute, and a lot of cardboard boxes! (See http://youtu.be/un1C9TkP7JU)

David Marshall, the lead author of the paper, says "we decided to put together a numerical simulation which would give a rough estimate of Batman's flight path and speed as he descended to the ground. To do this we took the physical laws which describe lift and drag on a wing and calculated Batman's motion in small steps along his descent.

We found that Batman's cape is too small for a safe glide. Although he would be able to travel around 350m before hitting the ground when jumping from a building 150m high, he would be travelling at around 50mph on impact, which wouldn't end too well. His velocity also quickly reaches a maximum, so even over short distances the glide would be far too dangerous.

This research may not be ground-breaking, but the process of producing the paper improved many skills which are important for any physicist such as problem solving, written communication, and team work."

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