Gravitation Question 211
Question: The condition for a uniform spherical mass m of radius r to be a black hole is [G= gravitational constant and g= acceleration due to gravity][AIIMS 2005]
Options:
A) $ [{{(2Gm/r)}^{1/2}}\le c] $
B) $ [{{(2Gm/r)}^{1/2}}=c] $
C) $ [{{(2Gm/r)}^{1/2}}\ge c] $
D) $ [{{(gm/r)}^{1/2}}\ge c] $
Show Answer
Answer:
Correct Answer: C
Solution:
Escape velocity for that body $ [v_{e}=\sqrt{\frac{2Gm}{r}}] $
$ [v_{e}] $ should be more than or equal to speed of light i.e.
$ [\sqrt{\frac{2Gm}{r}}\ge c] $
