AIPMT 2014 | Gravitation Question 31 | Physics

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?

10^$$-$$9 m

10^$$-$$6 m

10^$$-$$2 m

100 m

NEET 2013 (Karnataka)

MCQ (Single Correct Answer)

-1

A particle of mass 'm' is kept at rest at a height 3R from the surface of earth, where 'R' is radius of earth and 'M' is mass of earth. The minimum speed with which it should be projected , so that it does not return back, is
(g is acceleration due to gravity on the surface of earth)

$${\left( {{{GM} \over {2R}}} \right)^{1/2}}$$

$${\left( {{{gR} \over 4}} \right)^{1/2}}$$

$${\left( {{{2g} \over R}} \right)^{1/2}}$$

$${\left( {{{GM} \over R}} \right)^{1/2}}$$

NEET 2013 (Karnataka)

MCQ (Single Correct Answer)

-1

The radius of a planet is twice the radius of earth. Both have almost equal average mass densities. V_P and V_E are escape velocities of the planet and the earth, respectively, then

V_P = 1.5 V_E

V_P = 2 V_E

V_E = 3 V_P

V_E = 1.5 V_P

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