We can determine the speed of the Earth on its orbit by dividing the circumference to the period of time the Earth can complete one revolution around the Sun. First, convert years to seconds. The solutions is as follows:
V = (2πr/1 year) = (2π(1.5×10¹¹ m))÷(31536000 seconds)
V = 29,885.77 m/s
Then, 1 mile = 1609 m:
V = (29,885.77 m/s)(1 mile/1609 m)(3600 s/1 hr)
V = 66,866.87 miles/h
