Physics

Problem

Two satellites P and Q revolve in circular orbits of radii

4R

and

9R

respectively around the Earth (

R

is Earth’s radius). Which one of the following relations between their orbital speeds

v_{P}

and

v_{Q}

is correct? a)

v_{P}=\sqrt{2}\,v_{Q}

v_{P}=\dfrac{4}{9}\,v_{Q}

v_{P}=\dfrac{3}{2}\,v_{Q}

v_{P}=\dfrac{2}{3}\,v_{Q}