Question

A satellite is orbiting Earth in an approximately circular path. It completes one revolution each day (86,400 seconds). Its orbital distance is 22,500 kilometers from the Earth's center. What is the satellite's average speed?

Answer 1

For each revolution, the satellite covers the circumference
of its orbit.

The circumference of a circle is    (pi) x (diameter).

Since the satellite is 22,500 miles from the center, that number
is the radius of the circle.  The diameter is  45,000 miles.

The circumference is    (pi) x (45,000 miles) = 141,372 miles
                                                                        
The satellite's average speed is  141,372 miles per day, or

       (141,372 / 24) = 5,890 miles per hour

relative to the center of the Earth.