Physics Coursework Speech - Lead

Physics Coursework Speech

Dave King

12NI

Lead is one of the most widely used metals in the world but due to variable factors, it is rarely seen. It is normally hidden from view in such things as computer and TV screens, perfecting golf clubs, under car bonnets, batteries and probably most importantly radiation shielding. Contrary to popular belief lead is not used in pencils or household paint. But today I’m not hear to talk about everyday uses for but more specifically the role that lead plays in shooting and air rifle sports.

Lead is a bluish-white lustrous metal with the atomic symbol PB. It is extremely ductile and a poor conductor of electricity. It does not corrode easily but when exposed to air will tarnish. Lead has played a major part in shooting for generations as a reasonably cheap form of ammunition. The reason for this is that lead is a very dense metal (around 12000kg/m2 with a hardness of 1.5 and is therefore efficient at the penetration of living and non-living targets. If you look at this material selection chart you can see lead has a young’s modulus of around 16G/PA. This means that lead is a reasonably malleable material but also quite strong.

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There are many variances of lead pellets available for the many different aspects of shooting. As shown here, for instance, the spherical shape of this pellet increases the concentration of mass therefore increasing the penetration depth.

There are many advantages of using lead pellets for shooting, here are a few. 1. Although it is very dense, lead is also extremely malleable therefore making it easy to form and shape. Also lead is a quite abundant metal found worldwide therefore making it fairly cheap to buy. It is mined in most continents such as North America, South ...

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Contrasting with the many advantages of lead are the also plentiful disadvantages. The main disadvantage and also the reason lead was banned in wildfowling shooting, is the fact that it is a toxic material. It affects the gut, nervous system and causes anaemia. It is toxic by inhalation and ingestion. Because of this it was banned in wildfowl shooting because of the effects that it has on the soil that it lands in etc and any thing that grows on the land or eats the pellets.

For these reasons many companies are developing new lead free pellets in order to stop these effects. One example of this is the company Prometheus, who develop paragon pellets, these are said to be lead free but also improve the quality of the shooting performance. The pellet is said to consist of a polished zinc head (instead of lead) and a synthetic skirt. An advantage over lead pellets is the fact that when conventional lead pellets leave the barrel of an air rifle they are shown to considerably distort, where as the paragon pellet does not keeping air resistance to a minimum. As shown here. PIC OF DISTORTED PELLETS.

Not only by changing lead to zinc is pollution decreased, but performance is increased. The new materials used in the Prometheus pellet are said to produce a self-lubricating body for the pellet. This enables the pellet to travel at maximum velocity with least friction in the muzzle and therefore keeping the performance to the highest level. The co efficient of friction for lead is 1.5 where as the Prometheus pellet is 0.9. Another boast of the Prometheus pellet is that the highly polished head reduces air resistance. PIC OF PELLETS IN WIND TUNNEL

That’s basically all I have today, I hope you have enjoyed it and I will be willing to answer any questions you have to the best I can.