Question

a book is sitting on a desk. what best describes the normal force acting on the book? the upward force the desk pushes on the book the upward force the book pulls on the earth the downward force the book pushes on the desk the downward force the earth pulls on the book

Explanation:

To determine the normal force on the book, recall: Normal force is a contact force exerted by a surface (desk) on an object (book) perpendicular to the surface, opposing the weight.

• Option 1: The desk pushes the book upward (normal force, contact force from desk to book) – correct.
• Option 2: The book pulling Earth upward is gravity's reaction (not normal force).
• Option 3: The book pushing the desk downward is the book’s normal force on the desk (action - reaction, not the force on the book).
• Option 4: The Earth pulling the book downward is gravity (weight), not normal force.

Answer:

A. the upward force the desk pushes on the book