  The principles of static equilibrium are of special interest to civil
engineers. For a rigid body to be in static equilibrium the condition is that
net force and net torque acting on the body should be zero. That clearly
signifies that if equal weights are placed on either sides of a balance, the
balance should be in equilibrium, even if its beam is not horizontal (we have
considered the beam to be straight and have no thickness, an ideal case). Thus,
although the weights are equal, they will appear different which is puzzling.
This also shows that the concept of equilibrium is confusing, especially
neutral equilibrium is confused to be stable equilibrium. The study not only
throws more light on the concept of static equilibrium, but also clarifies that
a structure need not be firm and steady even if it is in static equilibrium.
