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Engineering Statics: Open and Interactive

Chapter 5 Rigid Body Equilibrium

In this chapter we will investigate the equilibrium of simple rigid bodies like your book, phone, or pencil. The important difference between rigid bodies and the particles of Chapter 3 is that rigid bodies have the potential to rotate around a point or axis, while particles do not.
For rigid body equilibrium, we need to maintain translational equilibrium with
\begin{equation} \sum \vec{F}=0\tag{5.0.1} \end{equation}
and also maintain a balance of rotational forces and couple-moments with a new equilibrium equation
\begin{equation} \sum \vec{M}=0\text{.}\tag{5.0.2} \end{equation}