Final answer:
When the net external force on an object is zero, the object can either be at rest or moving with a constant velocity, according to Newton's First Law of Motion. Acceleration indicates the presence of a net external force.
Step-by-step explanation:
Understanding Net External Force and Motion
According to Newton's First Law of Motion, an object will remain at rest or in motion at a constant velocity unless acted upon by a net external force. This means that when the net external force acting on an object is zero, the following statements can be true:
- The object is at rest.
- The object is moving with constant velocity.
Therefore, when the net external force is zero, it is not necessary for the object to be at rest; it could also be moving at a constant velocity. This encompasses both a stationary state and uniform motion (which includes zero velocity as a special case). An important point to remember is that a state of motion with constant velocity means there is no acceleration. Thus, if an object is accelerating, it indicates that there is a net external force acting on it.