Question

If the sum of all the forces acting on a body is zero, it may be concluded that the body

• A. Must be in equilibrium
• B. May be in equilibrium
• C. May be in equilibrium provided that forces are concurrent
• D. May be in equilibrium provided that forces are parallel

Answer 1

Answer:

C. May be in equilibrium provided that forces are concurrent

If the sum of all forces acting on a body is zero, it does not ensure that the body is in equilibrium. For instance, two equal and opposite forces acting at a distance apart cause rotation and not translational motion. However, if the forces are concurrent, the torque produced is zero, and the body is both translationally and rotationally stable.