Question

forces unit 1 test review complete the following sentence. if a book is sitting motionless on a table, ○ all forces acting on the book are balanced. ○ there are no forces acting on the book. ○ all forces acting on the book are unbalanced. ○ the only force is from the rock pushing on the table.

Explanation:

When an object is at rest (motionless), according to Newton's first law of motion, the net force acting on it is zero. This means the forces acting on it are balanced. Let's analyze each option:

• Option "all forces acting on the book are balanced": Correct. A motionless book has gravity pulling it down and the table pushing it up (normal force), and these two forces are equal in magnitude and opposite in direction, so the net force is zero (balanced forces).
• Option "there are no forces acting on the book": Incorrect. Gravity and the normal force from the table act on the book.
• Option "all forces acting on the book are unbalanced": Incorrect. Unbalanced forces would cause acceleration (change in motion), but the book is motionless.
• Option "the only force is from the rock pushing on the table": Incorrect. The question is about a book, not a rock, and this statement is irrelevant to the book's forces.

Answer:

A. all forces acting on the book are balanced