Which of the following best defines mechanical equilibrium?

Mechanical equilibrium occurs when an object is in a state where the net forces acting upon it are balanced, resulting in no acceleration. This concept can be analyzed through several perspectives.

When the forces are balanced, it implies that the object is either at rest or moving with a constant velocity, which means it has a constant speed with no change in its state of motion. Thus, even if the object's speed is constant, the absence of any resulting acceleration indicates that it is also in a state of zero acceleration.

Fundamentally, the criteria for mechanical equilibrium encompasses all these definitions: the forces acting on the object are balanced, leading to a constant speed or zero acceleration. Therefore, stating that mechanical equilibrium includes a state of constant speed, zero acceleration, and balanced forces encompasses the whole concept appropriately.

This comprehensive approach supports the idea that all the individual aspects contribute to a full understanding of mechanical equilibrium.