Physics of A black Hole

At the heart of a black hole is a point called a singularity. This point has no size and infinite density. In a black hole nothing can get a high enough escape velocity to escape it.  Physics for idiots used the analogy of shooting a cannon ball straight up. Eventually, the cannon ball would be pulled down by gravity right? Yes! Unless the Cannon ball is going fast enough to escape the Earth's gravitational pull.

               
    Since the kinetic energy of the escape velocity will be zero and the gravitational pull will be zero we can set the two equations together and solve for v to find the escape velocity. Where G is the Gravitational constant, M is the mass of the planet and r is the radius of the planet.

                                          v = sqrt((2*G*M)/r)                                                                                 (1)

When the force of gravity from a star becomes greater than the outward pressure of the temperature. The force make the star collapse pushing it's mass
inward, making the star denser and denser. Sometimes this super dense point becomes a black hole, but not always. For a star to become a black hole its needs to be compressed below the Schwarzschild Radius. The equation to find the Schwarzschild Radius is given below where G is the universal gravitational constant and c is the speed of light. Physic's for Idiots explained that if you want the earth to be a black hole it would need to be compressed to the size of the mosquito.

                            R = ((2G)/c^2)<                                                                          (2)

    https://i.stack.imgur.com/UZIKi.jpg