* Newtons are units of force, not mass: The question states "4.0 kg Newton force". This is incorrect. Kilograms (kg) measure mass, while Newtons (N) measure force.
* Forces always come in pairs: Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. This means that if the table exerts a force on the book, the book must also exert an equal and opposite force on the table.
Here's how we can rephrase and answer the question:
Question: A table exerts a 40 N force on a book which lies at rest on its top. What is the force exerted by the book on the table?
Answer: According to Newton's Third Law, the book exerts a 40 N force on the table, but in the opposite direction.
Explanation: Since the book is at rest, the forces acting on it must be balanced. This means the table's downward force of 40 N is counteracted by an equal and opposite upward force of 40 N exerted by the book. This upward force from the book is what keeps it from falling through the table.
