Chapter 33, Problem 19RQ

How does the mass of a star before its collapse compare with the mass of the black hole that it becomes?

To determine

The comparison between a mass of a star before its collapse and mass after it becomes black hole.

Answer to Problem 19RQ

The mass of the star remains the same before it collapses and after it becomes a black hole.

Explanation of Solution

The formation of a black hole happens when a supergiant star collapses into itself due to its high gravitational field. It is practically impossible for anything to be denser than a black hole. The lightest known black hole is of the mass five times that of the solar mass.

The gravitational pull of the black hole is super high that anything falling into it cannot escape light also and that’s why black holes are invisible. When the star collapses its mass remains the same, but the diameter reduces to several thousand kilometres which results in a very high-density of a black hole.

Conclusion:

Therefore, the mass of the star remains the same before it collapses and after it becomes a black hole.