Suppose a person weighs 100 pounds. If he travels to a planet with 5 times the mass of Earth and 10 times the radius of Earth, what will his new weight be?
1 Answer
5 lb
Explanation:
The weight of a person is the force that their mass exerts in the local gravitational field.
The force due to gravitation between two objects of masses
Let the person's mass be
On the other planet, the planetary mass is
So, perhaps counter-intuitively, the person will weigh only 1/20 as much on the surface of this much larger planet as they do on Earth's surface. If they weigh 100 pounds on Earth, then they will weigh 5 pounds on the second planet.