Engineering Mechanics Practice Exam 2026 – Comprehensive All-in-One Guide for Exam Success!

In static equilibrium, a rigid body has no motion or rotation. This means the sum of all external forces must be zero, so there is no translational acceleration. It also means the sum of all moments (torques) about any point must be zero, so there is no angular acceleration. Put simply: the resultant force is zero and the resultant moment is zero. If either were nonzero, the body would translate or rotate, contradicting static equilibrium. In practice, you ensure these two conditions by balancing forces to cancel the resultant force and balancing moments about a convenient point to cancel the resultant moment.