Q. Orbital velocity of earth’s satellite near the surface is $7\ km/s$. When the radius of the orbit is 4 times than that of earth’s radius, then orbital velocity in that orbit is
A) $3.5\ km/s$
B) $7\ km/s$
C) $72\ km/s$
D) $14\ km/s$
Explanation
(a) $v \propto \frac{1}{\sqrt{r}}$. If orbital radius becomes 4 times then orbital velocity will becomes half, $i.e.\frac{7}{2} = 3.5\ km/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.