Question

help with Order of Magnitude question?

The rate of motion of the earth at its equator is about 1,038 mi/h because of its rotation. From this information, estimate the earth's circumference using an order-of-magnitude estimate.

Question 21 options:

2,000 mi


20,000 mi


200,000 mi


2,000,000 mi

Answer 1

The rotation of Earth is equivalent to one day which is comprised of 24 hours. To determine the number of miles in Earth's circumference, one simply have to multiply the given rate by the appropriate conversion factor and dimensional analysis. This is shown below.
 
                  C = (1038 mi/h)(24 h/1 day)
                   C = 24,912 miles

From the given choices, the nearest value would have to be 20,000 mile. The answer is the second choice.