A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of the earth. Then,

Kepler's third law states that square of period of revoluation (T) of a planet around the sun, is proportional to third power of average distance r between sun and planet i.e. T² = Kr³ here K is constant. If the masses of sun and planet are M and m respectively then as per Newton's law of gravitation force of attraction between them is F = $${{GMm} \over {{r^2}}}$$, here G is gravitational constant. The relation between G and K is described as

Dependence of intensity of gravitational field (E) of earth with distance (r) from centre of earth is correctly represented by

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 $$ \times $$ 10²⁴ kg) have to be compressed to be a black hole?