Question

Orbital radius of a satellite S of earth is four times that of a communication satellite C. Period of revolution of S is

• A. $4$ days
• B. $8$ days
• C. $16$ days
• D. $32$ days

Answer 1

Answer: (B)

$8$ days

Time period of satellite depends only on radius of orbit and mass of the planet.

Using Kepler's law, $T^2\propto R^3$

Let $r$ be the radiius of communication satellite. Time period $T_1$ is $1$ day.

Thus, $\frac{T_2^2}{T_1^2}=\frac{(4r{)}^3}{r^3}$

$⟹T_2=8T_1=8days$