Question

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
• C. 182.5
• D. 730

Answer 1

The correct option is B

129

According to Kepler's law of period,
$\frac{T_1}{T_2}={\left(\frac{R_1}{R_2}\right)}^{\frac{3}{2}}={\left(\frac{R_1}{\frac{R_1}{2}}\right)}^{\frac{3}{2}}=2\sqrt{2}$
$\Rightarrow T_2=\frac{T_1}{2\sqrt{2}}=\frac{365}{2\sqrt{2}}days=129days$
Hence, the correct choice is (b).