If the principal stress values are $$120$$ MPa, $$-50$$ MPa and $$10$$ MPa in a given state of stress, then maximum shear stress in the material, in MPa, is _______.

A beam is loaded as shown in the figure

The bending moment, in $$Nm$$, at point $$R$$ is _______.

The room-temperature stress $$\left( \sigma \right)$$ - strain $$\left( \varepsilon \right)$$ curves of four materials $$P, Q, R$$ and $$S$$ are shown in the figure below. The material that behaves as a rigid perfectly plastic material is

In an off-set slider crank mechanism, shown in figure, the crank is rotated at a constant speed of $$150$$ rpm. The value of the angle $$\theta $$ shown in the figure is $${20^ \circ }$$ . What is the ratio of forward to return stroke time? Can this mechanism be used in an application involving quick return?