Equilibrium

Summary

Statics is the branch of mechanics dealing with forces acting on an object at rest.
Static Equilibrium (Point Bodies)
- A point body is in static equilibrium when the net force on it is zero.
- A point body in static equilibrium will not accelerate.
  It will remain at rest or continue moving with a constant velocity.
2 Forces in Equilibrium
- Two forces are in equilibrium if they are
  - equal (have equal magnitudes) and
  - opposite (180° apart).
3 Forces in Equilibrium
- Resultant-Equilibrant
  - Select 2 forces and find their resultant.
  - The remaining force is called an equilibrant if it is equal and opposite the resultant.
- Triangle of Forces
  - Three forces are in equilibrium if they can be arranged to form a triangle.
N Forces in Equilibrium
- Polygon of Forces
  - Three or more forces are in equilibrium if they can be arranged to form a polygon.
- Components
  - Resolve all forces into components in some convenient coordinate system.
  - Combine the components along each axis.
    (Add the components parallel to the axis and
    subtract the components anti-parallel to the axis.)
  - If the resultant along each axis is zero the object is in equilibrium.