The orbit is a circle. We need to find the circumference
of that circle to find out how far the object goes in one
orbit. 

Suppose the radius of the earth is R miles, then the object
is slinging around the center of the earth in a circle with 
a radius of R+215 miles.

So we calculate the circumference of that circle it travels
in



 miles it travels in one orbit. 

Now since 



We substitute  miles for the distance
and  hour for the time it takes to make 1 orbit.



or



If we assume the radius of the earth is R = 3959 miles,
then the speed is

  
 
Edwin