question_answer

A black hole is an object whose gravitational field is so strong that even light cannot escape from it. To what approximate radius would earth (mass \[=5.98\times {{10}^{24}}\,kg\]) have to be compressed to be a black hole? [NEET 2014]

A) \[{{10}^{-9}}m\]

B) \[{{10}^{-6}}\,m\]

C) \[{{10}^{-2}}\,m\]

D) \[100\,m\]

Correct Answer: C

Solution :

Problem Solving Strategy For the black hole, the escape speed is more than c (speed of light).

We should compare the escape speed with the (Note that the escape speed should be at least just greater than c)

New radius of the earth]