Question

Two satellites A and B go round a planet P in circular orbits having radii 4R and R respectively. If the speed of the satellite A is 3V, the speed of the satellite B will be

• A. 12 V
• B. 6 V
• C. 3/2 V
• D. 3/2 V

Answer 1

Answer: (B)

6 V

Answer 2

Orbital velocity of satellite $\therefore$ $v \propto \frac { 1 } { \sqrt { r } }$

$\Rightarrow$ $\frac { v _ { B } } { v _ { A } } = \sqrt { \frac { r _ { A } } { r _ { B } } }$ $\Rightarrow$ $\frac { v _ { B } } { 3 V } = \sqrt { \frac { 4 R } { R } }$ $\Rightarrow$ $v _ { B } = 6 V$ .