Statics and Torque
59 Introduction to Statics and Torque
What do a desk, a hospital bed, a bridge, a tree, and even the human skeletal system have in common—at least from the perspective of physics? All are systems that typically experience no net motion or acceleration. Whether naturally immobile or engineered to resist movement, these systems are in a state of mechanical equilibrium. This means that although forces act on them—such as gravity, tension, or compression—those forces are balanced. In physics terms, they have zero acceleration, and their velocity remains constant (usually zero).
This idea ties directly into Newton’s Second Law, which tells us:
When the acceleration [latex]\vec{a}[/latex] is zero, the net external force [latex]\vec{F}_{\text{net}}[/latex] must also be zero. This applies to both stationary objects and objects moving with constant velocity. In either case, they are said to be in equilibrium.
Statics
Statics is the branch of physics concerned with analyzing forces in systems that are not accelerating. This includes everything from bridges and scaffolds to the way bones support muscles or medical implants bear load. Statics is a special application of Newton’s laws that focuses exclusively on equilibrium—both in terms of linear motion and rotational stability.
In this chapter, we will explore the conditions required for an object or system to remain in equilibrium, including both the balance of linear forces and the balance of torques. We will also examine how forces can cause bending or deformation—even in equilibrium—and how engineers, biologists, and medical professionals use these principles to understand everything from bone strength to structural integrity in the human body and beyond.
