Black hole gravational pull vs neutron star ?

[Moviemann345]

When a neutron star flucuates into a black hole does the gravity increase tenfold? Or does the neutron star gravity (while turning into a black hole) increase as expected with the addition of more mass?

 

[Kevin_Axion]

I think it has the same mass as the neutron star, Black Holes are less massive then the Red Giant Stars that created them as the outerlayers are ejected and the dense core is suppressed into a point. The more mass/energy density concentrated in a specific region of spacetime creates more gravitation attraction. For instance you can have an object with a mass of 10^{10} kg distributed over a volume that is (10^5)^3 and have less gravitational attraction then a mass of 10^6 kg concentrated in a (10^{-2})^3 volume. I also have a question, do Black Holes obey the Pauli-Exclusion Principle?

 

[Janus]

The gravitational pull of a black hole of a given mass at a given distance is no stronger then the gravitational pull of a neutron star (or any other mass) at that distance. In other words, if the Sun were to collapse into a black hole, the orbit of the planets would remain unchanged.

What changes is that the smaller volume of the mass allows one to get closer to the center, and gravity follows an inverse square rule.

Thus if the Sun's present radius of 695,000 km were compressed down to the 3 km radius a black hole of its mass would have, then you would be able to get 231667 times closer to the center of the black hole and the gravity at the surface would be 5e10 times stronger.(however the gravity at 695,000 km from the center of the BH would be just as strong as it is at the surface of the Sun at present.