Chapter: Physics· JEE

If the distance between the earth and the sun were half its present value, the number of days in a year would have been

If the distance between the earth and the sun were half its present value, the number of days in a year would have been

(a) 64.5

(b) 129

(d) 730

Doubtly Asked 4 Apr 2021 Student doubt gravitation Save WhatsApp Report

1 answer

Best answer

The correct answer is 129 days option b

Explaination :

BY keplers third law \(T^2 \propto R^3\)

\(\therefore { ({ T_2\over T_1})^2=({ R_2\over R_1})^3}\)

T₁= 365 days , R₁ =R , R₂ = R/2

\({ ({ T_2\over 365})^2=({{ R_2/2}\over R_1})^3}\)

\(T_2^2={(365)^2\over8}\)

\(T_2^2=16653 \) ----{note: \(129^2=16641 \) but 16653 is nearby 129 hence due to option answer is 129}

\(T_2=129 \space days\)

Doubtly · 4 Apr 2021 Report

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