Geography: Assuming total mass of a star is ~ 1× 1033 kilogram (kg). about 0.1% of the star’s total mass will be used to make the nuclear reaction in the core to provide the energy for the star. the total energy corresponding to the mass of nuclear reaction can be computed by einstein massenergy relationship e = mc2, where e is energy, m is mass, and c is light speed (c = 3 × 108 meters/second). assuming the solar power (luminosity) of the star is 9 × 1025 w, which does not change during the lifetime of the

Assuming total mass of a star is ~ 1× 1033 kilogram

CristianPaz

06.01.2022

The correct answer is option B.

Explanation:

Einstein mass energy relationship

E = mc^2

Given mass of star = M = $1\times 10^{33} kg$

Mass of star used to make nuclear energy = m=0.1% of M

$m=\frac{0.1}{100}\times 1\times 10^{33}=10^{30} kg$

Speed of light = c = $3\times 10^8 m/s$

Nuclear energy generated = E

$E=mc^2=10^{30} kg\times (3\times 10^8 m/s)=9\times 10^{46} J$

Solar power of the Star,P = $9\time 10^{25} Watts$

Total life time of the star = T

$Power=\frac{Energy}{Time}$

$Time =\frac{Energy}{Power}$

$T=\frac{9\times 10^{46} J}{9\time 10^{25} Watts}$

$T=1\times 10^{21} seconds$

Total life time of the star is $1\times 10^{21} years$ .

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