A black hole is an object whose gravitational fields is so strong that even light cannot escape from it. To what approximate radius would earth (mass = 5.98 × 1024 kg) have to be compressed to be a black hole?
Answer & explanation
Correct answer: option 3
Escape velocity : v = \(\sqrt{\frac{2GM}{R}}\)
c= speed of light
c= \(\sqrt{\frac{2GM}{R}}\)
squaring both sides
R = \(\frac{2GM}{c^2}\) = \(\frac{2×6.6×10^{-11}×5.98×10^{24}}{(3×10^8)^2}\)
= 10-2m