Question

An object at the surface of Earth (at a distance R from the center of Earth) weighs 90 N. Its weight at a distance 3R from the center of Earth is approximately:

A) 180 N
B) 90N
C) 45N
D) 23 N
E) 10 N

Answer 1

The weight of an object that is 90 N at the surface of Earth would be 10 N at a distance of 3R from the center of Earth due to the inverse square law of gravitation.

Step-by-step explanation:

The question asks for the weight of an object when it is at a distance of 3R (three times the radius of Earth) from the center of the Earth compared to its weight at the surface. Weight can be calculated using the formula w = mg, where m is mass and g is the acceleration due to gravity. On Earth, g is approximately 9.80 m/s², and weight varies with the inverse square of the distance from the center of Earth according to Newton's Universal Law of Gravitation.

Since the weight at the surface is 90 N, at a distance 3R, the acceleration due to gravity would be nine times less (as g varies inversely with the square of the distance). Therefore, the weight of the object at a distance of 3R would be 90 N divided by 9, which equals 10 N. So the correct answer is E) 10 N.