Question

True or false: A physics book on a table will not move at all if and only if the net force is zero.

Short answer

Answer: Yes, the statement is true. A physics book on a table will not move at all if and only if the net force acting on it is zero, as confirmed by Newton's first law of motion.

Step-by-step solution

To examine the statement

We will first break down the statement which says "A physics book on a table will not move at all if and only if the net force is zero." We need to check if not moving at all is equivalent to having zero net force.

Understanding Newton's First Law of Motion

Newton's first law of motion, also known as the law of inertia, states that an object at rest will stay at rest and an object in motion will stay in motion with the same speed and direction, unless acted upon by an external force. In other words, an object will maintain a constant velocity (or stay at rest) if the net force acting on it is zero.

Evaluating the scenario

Let's consider the physics book on a table. When it's at rest, the force of gravity acting on the book (downward direction) is balanced by the normal force exerted by the table (upward direction). Since these two forces have opposite directions and equal magnitudes, the net force acting on the book is zero. To verify the statement, we need to consider two cases: 1. If the net force is zero, the book will not move at all. 2. If the net force is not zero, the book will move. In the scenario provided, if the net force is zero, the book indeed will not move at all due to Newton's first law of motion. Now let's consider the case where the net force is not zero. If an additional force, such as a push or pull, acts on the book, the balance between the gravitational force and the normal force will be disrupted. This results in a net force that is not zero, causing the book to move, verifying the second case.

Conclusion

Based on the analysis of the statement and the examination of both cases, we can confirm that the statement is true. A physics book on a table will not move at all if and only if the net force acting on it is zero.