CGPET 2021 Solved Paper

Given, mass of earth, m=5.98×1024‌kg
speed of light, c=3×108m∕s
Gravitational constant,
G=6.67×10−11N−m2∕kg2
For earth to be black hole, the escape velocity should be at least equal to speed of light.
∴ Escape velocity = speed of light
√2

Gm

R

=c
⇒R=

2‌Gm

c2

=

2×6.67×10−11×5.9×1024

(3×108)2

=

2×6.67×598×10−11×1024

104×9×1016

=

1334×598

9

×10−31×1024
=10−2m