Taking that earth revolves round the sun ina circular orbit of radius `15xx10^10` m, with a time period 1 yr the time taken by another planet , which is at a distance of `540 xx 10^10` m, to revolve rounnd the sun in circular orbit once , will be

Options

A. 216 yr
B. 144yr
C. 72yr
D. 36yr

Answer

A

Explanation

`((T_1)/(T_2))^2 = ((R_1)/(R_2))^3`
Rightarrow `((1)/(T_2))^2 = ((15xx10^10)/(540xx 10 ^10))^3`
therefore `T_2 = (36)^3/2 = (6)^3 = 216 yr`