Problem:
The radius of Earth at the equator is approximately miles. Suppose a jet flies once around Earth at a speed of miles per hour relative to Earth. If the flight path is a negligible height above the equator, then, among the following choices, the best estimate of the number of hours of flight is
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The length of the flight path is approximately the circamference of Earth at the equator, which is
The time required is
so the best choice is hours.
Query. What is a negligible height; i.e., for which heights above the equator would the flight-time be closer to choice than to