A book weighing 15 N rests on a table. Which pair of forces represents a Newton's third law action-reaction pair?
AThe book's weight and the normal force from the table.
BThe Earth's gravitational pull on the book, and the book's gravitational pull on the Earth.
CThe normal force on the book, and the book's weight.
DThe normal force on the book, and the book's weight added together.
Explanation
📌 Newton's third law pairs act on DIFFERENT objects. The Earth pulls the book down; the book pulls the Earth up — that is the pair, both gravitational. Distractor A and C describe forces on the SAME object (the book) that happen to cancel — that is equilibrium, not action-reaction. This is the single most common third-law error on the CBE.