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

$\frac{T_1}{T_2}=(\frac{R_1}{R_2}{)}^{3/2}=2^{3/2}$.

Hence,$T_2=\frac{T_1}{2\sqrt{2}}=\frac{365}{2\sqrt{2}}=129$ days.