NETA Personal Trainer Practice Exam

According to Newton's first law, what happens to an object at rest?

1. It eventually moves without external force

2. It stays at rest unless acted upon by an unbalanced force

3. It begins to accelerate

4. It remains in motion indefinitely

The correct answer is: It stays at rest unless acted upon by an unbalanced force

Newton's first law of motion, often referred to as the law of inertia, states that an object at rest will remain at rest unless acted upon by an external unbalanced force. This principle emphasizes that without an external force, there is no change in the state of motion of the object, meaning it will not spontaneously start moving on its own. In the context of this law, the focus is on the concept of balance of forces. An object at rest has no net forces acting on it; thus, it doesn't move unless influenced by an outside force that disrupts this state. This law applies not only to objects at rest but also to objects in motion, indicating that they will maintain their state of motion unless acted upon by an unbalanced force. The other options suggest movements or changes in states that contradict the principle of inertia. For instance, suggesting that an object will eventually move without an external force misinterprets the concept of inertia. An object will only move as a direct result of an applied force, adhering to the law proposed by Newton.