Three books (X, Y, and Z) rest on a table. The weight of each book is indicated. The net force acting on book Y is:
A) 4 N down
B) 5 N up
C) 9 N down
D) zero
E) none of these

Question

Three books (X, Y, and Z) rest on a table. The weight of each book is indicated. The net force acting on book Y is: 
A) 4 N down 
B) 5 N up 
C) 9 N down 
D) zero 
E) none of these

Quizplus · Accepted Answer

The net force acting on book Y is zero, since the forces acting on it are balanced. Book X is exerting a force of 4 N down and book Z is exerting a force of 4 N up, resulting in a net force of zero.

Three Books (X, Y, and Z) Rest on a Table