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

Options

A. 64.5
B. 129
C. 182.5
D. 730

Answer

B

Explanation

According to Kepler's law , `T_1^2/T_2^2 =R_1^3/R_2^3 , T_1`=365 days , `T_2`=? , `R_1=R,R_2=R/2`
`rArr T_2=T_1(R_2/R_1)^(3//2) =365[(R//2)/R]^(3//2)` = 129 days