An abject is orbiting the Earth at 215 miles in altitude. It takes one hour to orbit the Earth. What is it\'s speed? What is the mathmatic equation to calculate the answer? Solution We know the earth\'s radius = 3960 miles. and the radius with object = 3960 miles + 215 miles = 4175 miles and the circumference of earth with respect to object = 2pi*4175 miles = 26232 miles and Given time = 1 hr then speed = distance/time = 26232 miles/1 = 26232 mph.