Nuclear Physics

A question from Atoms & Nucleus Decay

Plutonium decays with a half-life of 24000 years.If plutonium is stored for 72000 years.What fraction of it remains?

Asked Vikas

Usage of energy in nuclear fission and fusion

I read in a biographic book about Albert Einstein that the energy produced from burning materials is much less than the energy stored in them (the authored suggested the book itself as an example – he wrote that it can power a ship for about 100 years).
I would like to know how much of the energy of a material is used in nuclear fission and fusion.

Asked Avishag

Answer:

Nuclear Explosion (Source: WIkiPedia)

Energy obtained by burning a substance is meagre compared to the energy contained in it. According to Einstein’s mass energy relation (E=mc²), the energy released by converting 1 gram of any substance completely into energy = 0.001 (mass) x 300,000,000 x 3,00,000,000 (square of velocity of light).

But, in nuclear reactions, the entire mass is not converted into energy. The tremendous energy liberated during a nuclear explosion is the result of a small portion of the mass of nucleus undergoing the reaction getting converted into energy.

For example, when a uranium 235 atom undergoes nuclear fission the enrgy liberated is 200 MeV = 200 x 1.6 x 10 -19 J

In 235 g of U-235 there are 6 x 10²³ atoms.

So if that much of U-235 atoms undergo fission, the energy liberated will be about 1,00,00,000 J.

Hope that you might have had an idea of it.

Thoughts on Higgs Boson

When it is not contested scientifically that change is a continuous phenomenon,how is that Higgs boson, if found,can be considered as the ultimate building block of matter.

Sure, it may prove a mathematically arrived conclusion… yet the contradiction remains.
An ever changing, at the same time, ever stable (because it is the ultimate one) is the contradiction.
One may find changing or divisible particle only…

(Posted by K.C. Muralidhar)

Please post your thoughts and reactions as comments to this post

Is it possible to stop a nuclear reaction once started?

Is it possible to stop a nuclear reaction,after starting it ( I’m not only talking about reactor, but in nuclear bombs too ). If it’s possible then which laws will fail or If It is impossible then Why? …………. have any country have prepared about It? (Asks George)