# Nuclear Energy.

Essay by stewie23High School, 12th grade October 2005

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* In the 1930's nuclear energy became a serious possibility.

* 1932 - Discovery of the neutron.

* No change, ergo, can probe nucleus.

* Hahn and Strassmann fired neutrons at U nucleus.

* Lise Meitner and Otto Frisch interpreted this:

Neutrons caused splitting of U into smaller nuclei

* Fission had occurred.

* Potent source of energy!

* Energy from

E=mc2

* In more complete form, Einstein showed that at relativistic speeds we cannot use k=(0.5)mv2 .

* Remember from special relativity, that as speed increases, mass increases!

* ie. Work is done on a body: K increases.

* Or Work is done on a body: mass increases.

* Then ENERGY transforms into Mass.

* Einstein:

Instead of k=(0.5)mv2

We must use

K=(m-m0)c2

Or K = mc2-m0c2

As K = E-m0c2

E=m0c2+K

Where E = total energy.

* What does E=mc2 mean?

* It means that mass is a form of energy.

* In principle, we could transform mass into other forms of energy.

* Eg. Convert 1 kg of mass into heat

E=(1)(3.0x 108)2 = 9.0x1016 J.

* Consider a fission reaction:

10n + 23592U = 14038Xc + 9438Sr + 210n

* The mass of products is less than the mass of the reactants!

ie. 23592U 235.0439 u 14038Xc 139.9054 u

n 1.008 u 9438Sr 93.9063 u

210n 2.016 u

236.0519 u 235.8277 u

Difference = 0.2242u ( or about 0.0095%)

The difference is small, but the c2 term means the energy will be large.

This introduces an idea called BINDING ENERGY, which we will consider.

Key Idea:

When individual; nucleons are brought together to from nuclei; the mass of the nucleus is less than that of the sun of the sum of the masses of the individual nucleons when they are widely separated. Energy is therefore...