Question

The weight of a person on or above the surface of the earth varies inversely as the square of the distance the person is from the center of the earth. If a person weighs 180 pounds on the surface of the earth and the radius of the earth is 3900 miles, what will the person weigh if he or she is 325 miles above the earth's surface?

Answer 1

Weight = k/(distance)². Let's find the value of k when distance = earth radius:

180 = k/(3900)² → k = 180 x 3900² → k = 2,737,800,000

If he is at 325 miles ABOVE the earth, the distance becomes: 3,900+325=4,225 miles and his weight becomes:

Weight = k/(distance)² → Weight = 2,737,800,000/(4225)² = 153.37

Weight = 153.37 lb