Quote (rfbfire @ Tue, Jan 6 2009, 01:10pm)
My question is, if density has no correlation with gravitation, only mass, and the average black hole is roughly 10 times the mass of our sun(smaller than many other stars) then, why is there such an comparatively stronger gravitational pull coming from black holes than a star of the same mass? I should mention, Astronomy is not my strong suit and I apologize if this is a stupid question.
to add what bes said, black holes are only infinitely stronger when you are very close to them because the radius shrinks by enormous scales. an event horizon (which is the edge of the infinite gravitationl pull) is very close to the black hole so according to the equation of Gconstant*M1*M2/r, where r is the distance between the two oibjects, one can see why a black hole of enormous mass would have an enormous pull when youre close. since ALL of the mass is packed into a tiny spot, ALL the gravity of felt from that mass. whereas a star (4 km from the center [where the event horizon WOULD be]) has mass all around it, so the net force acting on that spot is not at all as strong.
this help?