Nuclear Physics And Radioactivity Question 98
Question: The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is 1 4 kilowatt/ $ m^{2} $ . The average earth- sun distance is $ 1.5\times 10^{11} $ meters. The mass lost by the sun per day is (1 day = 86400 seconds)
Options:
A) $ 4.4\times 10^{9},kg $
B) $ 7.6\times 10^{14},kg $
C) $ 3.8\times 10^{12},kg $
D) $ 3.8\times 10^{14},kg $
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Answer:
Correct Answer: D
Solution:
[d] energy radiated $ =1.4KW/m^{2} $ $ =1.4KJ/\sec m^{2}=\frac{1.4kJ}{\frac{1}{86400}day,m^{2}}=\frac{1.4\times 86400}{day,m^{2}} $ Total energy radiated/day $ =\frac{4\pi ,{{(1.5\times 10^{11})}^{2}}\times 1.4\times 86400}{I}\frac{kJ}{day}=E $
$ \therefore $ $ E=mc^{2}\Rightarrow m=\frac{E}{c^{2}} $ $ =\frac{4\pi {{(1.5\times 10^{11})}^{2}}\times 1.4\times 86400}{{{(3\times 10^{8})}^{2}}}=3.8\times 10^{14}kg. $
BETA
