An astronomy textbook, when printed out, weighs four pounds on the surface of the Earth. After finishing your course, you are so tired of the book, you arrange for NASA to shoot it into space. When it is twice as far from the center of the Earth than when you were reading it, what would it weigh? (Note, assume that the book has been moving away from the Earth, not falling freely around it.)
A) 4 lbs
B) 8 lbs
C) 2 lbs
D) 1 lb
E) 16 lbs

Question

Quizplus · Accepted Answer

The weight of an object in space is determined by the force of gravity acting upon it, which is a function of the mass and distance between two objects. As the book moves away from Earth, the distance between it and Earth increases, causing the force of gravity to decrease. When the book is twice as far from the center of the Earth, the distance between it and Earth has doubled, causing the force of gravity to decrease to one-fourth of what it was before. Therefore, the book would weigh one-fourth of its original weight, or 1 pound.

An Astronomy Textbook, When Printed Out, Weighs Four Pounds on the Surface