Question

1. what is the escape velocity ?

2. what are the two factors that determine the value of the escape velocity?

3. what are black holes? Why are they called "black"?

Answer 1

1. The velocity required to escape the gravitational field of the planet is called Escape velocity. It is the minimum velocity that the object must have to escape the gravitational field. The earth's escape velocity is

v_e=(2GM/R)^1/2=11 km/sec

Where,

G=Gravitational constant

M=Mass of earth

R=Radius of earth

2.Escape velocityv_e=(2GM/R)^1/2

As we can see Escape velocity depends upon Mass of the planet, and radius of the planet.

3. Black holes are the place in the space that attracts all the nearby particles as well as electromagnetic radiation in it. It has the strongest gravitational pull such that it attracts light also.

As the light also can't escape from its pull so they are called Black Holes.