The principle of superposition is made use of in structural computations when:

The magnitude of the only shear stresses acting at a point in plane stress situation is $$7.5\,N/n{m^2}.$$ The magnitudes of the principle stresses will be:

A cylindrical tank of radius $$'r'$$ and wall thickness $$'t'$$ has flat end closures. The tank is subjected to an internal pressure $$P.$$ The longitudinal $$\left( {{\sigma _x}} \right)$$ and the circumferential $$\left( {{\sigma _\theta }} \right)$$ stresses respectively are given by:

A rigid rod $$AB$$ of length $$L$$ is hinged at $$A$$ and is maintained in its vertical position by two springs with spring constants $$K$$ attached at end $$B.$$ The system is under stable equilibrium under the action of load $$P$$ when $$P < \,{P_{Cr}}$$. The system will be in unstable equilibrium when $$P$$ attains a value greater than