A man pushes horizontally on the book with force and moves it at constant speed along the table. Three "agents" exert forces on the book, shown as , , and in the second diagram, and three "agents" exert forces on the table, shown as , , and in the third diagram. The "action-reaction" forces of Newton's third law are
A) and .
B) and .
C) and .
D) and .
E) and .

Question

A man pushes horizontally on the book with force  and moves it at constant speed along the table. Three "agents" exert forces on the book, shown as  ,  , and  in the second diagram, and three "agents" exert forces on the table, shown as  ,  , and  in the third diagram. The "action-reaction" forces of Newton's third law are
A) and . 
B) and . 
C) and . 
D) and . 
E) and .

Quizplus · Accepted Answer

According to Newton's third law, for every action, there is an equal and opposite reaction. In this case, the action force is the man pushing the book with a force of 11eaa4be_83d6_6a37_9e4a_eda84d266a33_TB6080_11, and the reaction force is the book pushing back on the man with a force of equal magnitude and opposite direction, 11eaa4be_83d7_c9d4_9e4a_b367c837001c_TB6080_11. Similarly, the forces exerted on the book by the "agents" are the action forces, and the forces exerted on the table by the book are the reaction forces. The only pair of forces that satisfy the conditions of Newton's third law are 11eaa4be_83d7_c9d4_9e4a_b367c837001c_TB6080_11 and 11eaa4be_83d7_f0e5_9e4a_ab573d226208_TB6080_11, as they are equal in magnitude and opposite in direction. Therefore, the correct answer is D.

A Man Pushes Horizontally on the Book with Force