Final answer:
Balanced forces maintain an object's current state of motion, while unbalanced forces lead to change in motion or acceleration. Stable equilibrium allows an object to return to its original position after disturbance, while unstable equilibrium leads to the object moving away.
Step-by-step explanation:
When discussing the effects of balanced and unbalanced forces on an object's motion, we are touching on some fundamental principles of physics. A balanced force situation occurs when the net force acting on an object is zero, which means the object will maintain its state of motion; it will either remain at rest or continue to move at a constant velocity if it was already in motion. This can be seen when an object is lifted by a crane and remains at rest at the start and end of the motion; the forces are in equilibrium.
An unbalanced force, on the other hand, means the net force is not zero, leading to a change in motion or acceleration of the object in the direction of the resultant force. The different accelerations produced when the same force is applied to systems of different masses, such as a basketball versus a stalled SUV, exemplify this concept. The basketball accelerates much more due to its smaller mass compared to the SUV. Furthermore, stable and unstable equilibrium points demonstrate how the direction of net force can affect an object's return to equilibrium.
For instance, if an object at stable equilibrium is disturbed, the resulting forces will bring it back to that point, as seen with a marble in the bowl that oscillates around the equilibrium point when slightly disturbed. Conversely, an object at an unstable equilibrium, like a marble balanced on an upside-down bowl, will roll off when disturbed because the forces are directed away from the equilibrium point. This explains why certain systems come to rest; they are influenced by forces that ultimately balance out or reach an equilibrium where further movement ceases.