Question

If a new planet is discovered rotating around sun with the orbital radius double that of the earth, then what will be its time period? (in earth's days) (Take $\sqrt{2}=1.4$ )

• A. 1032
• B. 1023
• C. 1024
• D. 1043

Answer 1

Answer: (A)

1032

Answer 2

By Kepler's third law, $T^{2} \propto R^{3}$ $\therefore \left(\frac{ T _{2}}{365 \text { days }}\right)^{2}=\left(\frac{2 r }{ r }\right)^{3}$ $T _{2}=365 \times 2 \sqrt{2}=1032$ days