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Interesting Findings And World Unfolding Through My Eyes.

Sunday, September 30, 2007

The Making Of ARCHERY

Don't let the word 'physics' put you off - read the article for an insight into how modern science can help us understand the history of the weapon we now use for sport (and ignore the formulae if you must!) It is generally believed that the main factor responsible for the English victory at the battle the Agincourt in 1415 was the longbow. Gareth Rees describes from a physicist's point of view why we believe this simple weapon was so devastatingly effective.
In 1415 King Henry V of England took a small army to France to try to enforce the English claim to the French throne. By late autumn things were not going well for the English. The weather was poor, and Henry's army was short of provisions, exhausted, and badly stricken with dysentery. Henry decided to make for his stronghold at Calais for the winter, but the French saw an opportunity to annihilate the English forces and advanced with a huge army to do battle.

The two armies met at the little village of Agincourt on the evening of 24 October, after the English forces had marched 260 miles in 17 days. King Henry's offer to buy peace was rejected, and on the following afternoon one of the decisive battles of the Hundred Years' War took place.

The battle of Agincourt has entered English folklore - and, indeed, popular culture as a result of the Laurence Olivier and Kenneth Branah film versions of Shakespeare's Henry V. No more than 6000 soldiers in the service of the English king faced about 50,000 French soldiers. Apart from the gross disparity in numbers, the other substantial difference between the two armies was in their use of the longbow. The English army was composed largely of bowmen (about 80%), whereas the French used virtually none.

The massive French cavalry charge was met by a storm of English arrows, as a result of which the cavalry fled back through the front columns of the French infantry. The English soldiers waded into the chaos armed with hatchets and billhooks and, backed up by their own small cavalry and the threat of their longbows, succeeded in dispersing the whole French army.

The bow - any bow - is basically a spring. The archer does work on this spring as he draws the bow, storing potential energy in the elastically deformed bowstave. When he releases the string, some of this potential energy is converted into kinetic energy of the arrow, through the action of the tension in the bowstring accelerating the arrow, the arrow leaves the bow at high speed and wings its way towards its target. Its orientation is stabilised by three fletchings at the rear of the arrow.

If we draw a graph of the force F needed to draw the arrow back through a distance x, the area under the graph represents the work done on the system and hence the potential energy stored in the bow. If the graph is a straight line through the origin (i.e. the bow behaves like a spring that obeys Hooke's law), this energy will be equal to Fx/2 ).
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Posted by Ajay :: 6:57 PM :: 0 comments

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