Boomology – The science behind nuclear explosions (updated with Tsar Bomba!) (updated again!)
The world was changed forever in 1945. The Manhattan project tested the first ever “atomic bombs” and the power that was contained in the nucleus was unleashed. The first ever atomic bomb blast was a test called Trinity, detonated on July 16th in New Mexico, USA.
It was called “The Bomb” and its effects still change the world today. The “nuclear powers” of the world are those nations that have (or are suspected to have) nuclear weapons. Ever since the first military detonation (Hiroshima), the nations of the world have sought to prevent the further spread of this deadly technology. Depending on who you consult, you will get explanations ranging from desire to maintain the nuclear nations’ political power through to altruism to remove the risk by destroying all nuclear weapons. The total nuclear arsenal of all nations is more than enough to destroy all life on earth many times over. Despite this danger, some argue that the nuclear bomb technology has been the greatest force for peace in modern history; that without it many more conventional (non-nuclear) wars would have been fought, or that World War two may have continued for many more years, resulting in even more loss of life.
As we know from the last unit of study, it is not the explosion that is the most critical damage that is done by a nuclear bomb, even though that is nothing to be scoffed at, but it is the aftereffects. Fallout is a harmless sounding word that conceals the true horror of atomic weapons – the fact that even after the explosion, the very land, air and water are poisoned; uninhabitable for many thousands of years due to the radioactive materials spread by the explosion. Fortunately, the only two bombs ever used in was were so small that the fallout effects were very minor, and have almost completely dissipated now.
But the potential of the nuclear science is far more than just weapons – nuclear power is a power source of almost unlimited potential for the whole human race. Nuclear power is “carbon neutral”, meaning that it does not directly produce any carbon dioxide in the process of generating energy, Energy dense, meaning that a small amount of fuel can release a large amount of energy, and produces base-load power, which means it is suitable for providing energy for large cities (unlike renewable power sources such as solar, wind and tidal power which can produce power in an intermittent way which makes it unreliable for mass usage).
But for all it’s advantages, Nuclear Power is not currently used to produce power for Australia (in fact, only France uses nuclear power to provide a majority of it’s power needs). This is primarily because of two reasons – fear of catastrophic failure (“Meltdown” – what happened in Chernobyl) and concerns over waste disposal. We will deal with these in more detail over this unit (and in the next post!).
But how does it actually happen? What happens inside a nuclear reactor or nuclear bomb that releases so much energy? Well, it is all about a certain famous formula:
What does this equation mean? Well for a start it is presented incorrectly in most circumstances – it is actually:
This shows you that this equation is all about the change in (that’s what the Δ (delta) symbol means) energy and mass. The first application is obvious – that when mass is destroyed, a large amount of energy is released (equal to the mass times the speed of light squared). The second application is less obvious – that energy itself has mass. When an object gains energy – for example by heating up (gaining heating energy) or moving fast (kinetic energy) – it also gains mass. The amount of mass is miniscule in most common situations.
The second aspect is even stranger – that if you weigh nucleons separately that weigh more than when they are put together. This difference is called a mass deficit and the missing energy is converted into energy. This energy varies with the number of nucleons, and demonstrates the difference between fission and fusion.
This process is explained in the supplementary notes and here is some more reading to help you understand this complex topic (1,2). I also encourage you all to read the furry elephant explanation – make sure you check out all the animations!
And last of all – here are some excellent videos to help you see what we are talking about. This is the first one:
Remember – you will only get out of physics what you put in! So comment!
See you in class!
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