Final answer:
An object in equilibrium must either be moving with constant velocity or at rest, according to Newton's first law of motion. Acceleration involves changes in velocity or direction, not maintaining a constant velocity. Momentum is conserved in isolated systems with objects in motion and at rest.
Step-by-step explanation:
If an object is in equilibrium (where the net force Fnet is zero), it must either be moving with constant velocity or at rest. This is because according to Newton's first law of motion, also known as the law of inertia, an object will remain at rest or move at a constant velocity unless acted upon by a net external force. If there is no net external force, implying that the net force is zero, the object's velocity will not change; therefore, it must either continue in a state of rest or continue moving with a constant velocity.
Check Your Understanding:
- Ways an object can accelerate: An object can accelerate by speeding up, slowing down, or changing direction. Maintaining constant velocity is not a form of acceleration.
Considering an object in uniform motion, such as two objects colliding where external forces are not present, the conservation laws state that momentum is conserved. If one object is at rest and another is moving with constant velocity, after collision, the first object may start moving while the second object comes to rest, illustrating the case where the net force is zero.