Q. A geostationary satellite is orbiting the earth at a height of 5R above the surface of the earth, R being the radius of the earth. The time period of another satellite in hours at a height of 2R from the surface of the earth is
A) 6/√2
B) 5
C) 10
D) 6√2
Explanation
[Solution from source] Orbit radii are 6R (geostationary, T = 24 h) and 3R (height 2R). By Kepler's law T ∝ r^(3/2): T = 24 × (3R/6R)^(3/2) = 24/(2√2) = 6√2 h. Using heights (5R and 2R) instead of orbital radii gives a wrong value. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.