A straight turning operation is carried out using a single point cutting tool on an $$AISI$$ $$1020$$ steel rod. The feed is $$0.2$$ $$mm/rev$$ and the depth of cut is $$0.5$$ $$mm.$$ The tool has a side cutting edge angle of $${60^ \circ }.$$ The uncut chip thickness (in $$mm$$) is _______________

Cutting tool is much harder than the work piece. Yet the tool wears out during the tool-work interaction, because

Which pair of following statement is correct for orthogonal cutting using a single-point cutting tool?
$$P.$$ reduction in friction angle increases cutting force
$$Q.$$ Reduction in friction angle decreases cutting force
$$R.$$ Reduction in friction angle increases chip thickness
$$S.$$ Reduction in friction angle decreases chip thickness

The diameter of a recessed ring was measured by using two spherical balls of diameter $${d_2} = 60mm$$ and $${d_1} = 40mm$$ as shown in the figure.

The distance $${H_2} = 35.55\,\,mm$$ and $${H_1} = 20.55\,\,mm$$. The diameter ($$D,$$ in $$mm$$) of the ring gauge is __________________.