A weight watcher who normally weighs 400 N stands on top of a very tall ladder so she is one Earth radius above the Earth's surface. How much would she weigh there?
A) 100 N
B) 400 N
C) 200 N
D) 0
E) none of these

Question

Quizplus · Accepted Answer

The gravitational force (and thus weight) decreases with the square of the distance from the center of the Earth. If you are one Earth radius above the surface, you are twice as far from the center, so your weight is (1/2)^2 = 1/4 of what it is on the surface. Therefore, 400 N becomes 100 N.

A Weight Watcher Who Normally Weighs 400 N Stands on Top