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| 1. |
What are the three conditions for static equilibrium? |
| Answer» EXPLANATION:A body is in equilibrium when it REMAINS either in uniform motion (both translational and rotational) or at rest. When a body in a selected inertial frame of reference neither ROTATES nor moves in translational motion, we say the body is in static equilibrium in this frame of reference. Conditions for equilibrium require that the sum of all external forces acting on the body is zero (first condition of equilibrium), and the sum of all external torques from external forces is zero (second condition of equilibrium). These two conditions must be simultaneously satisfied in equilibrium. If one of them is not satisfied, the body is not in equilibrium. The free-body diagram for a body is a useful tool that allows US to count correctly all contributions from all external forces and torques acting on the body. Free-body diagrams for the equilibrium of an extended rigid body must indicate a pivot point and lever arms of acting forces with RESPECT to the pivot. | |