# What physical law explains why matter flowing from the companion star orbits rapidly as nears the black hole?

##### 1 Answer

Gravity explains why matter orbits a black hole rapidly.

#### Explanation:

Newtons equations the motions of objects in orbit. The force of gravity acting on a an object is described by the equation:

Where

The centripetal force required to keep an object in orbit is given by the equation:

Where

When an object is in orbit these two forces are equal:

Dividing by

In the scenario

Hence the closer matter is to the black hole the faster it will orbit.

Once matter gets quite close to a black hole the effects of general relativity become significant, but Newtons equations of motion are close enough at greater distances.