» Esercizi svolti di Matematica e Fisica

Kinetic energy above which: a) a neutron and b) an electron may be considered relativistic

giovedì, Dicembre 31st, 2020

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Exercise of Nuclear reactor physics by ing. Giorgio Bertucelli.

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Estimate the speed, in m /s , and the kinetic energy, in MeV , above which: a) a neutron and b) an electron may be considered relativistic.

Solution
The rest mass of a neutron n is:

The rest mass of an electron e is:

A relativistic body is one whose speed V is >10/100 of light speed c=3·10^8 m/s. The relativistic mass m' of a body is related to rest mass m by

If the ratio V/c >= 0.1 we can write

Relativistic kinetic energy of n

Relativistic kinetic energy of e

(altro…)

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Calculate the average density of nuclei

martedì, Dicembre 29th, 2020

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Exercise of Nuclear reactor physics by ing. Giorgio Bertucelli.

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Calculate the average density of nuclei in g cm³. If the earth has a mass of 5.98·10kg and an equatorial radius of 6378km, what radius would it have if it were made entirely of closely packed nuclei (one third voids)?

Solution
The compact volume of the earth would be 2/3 of the current volume:

then the average density would be

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