Spot welding of two $$1$$ $$mm$$ thick sheets of steel (density $$ = 8000kg/{m^3}$$ ) is carried out successfully by passing a certain amount of current for $$0.1$$ second through the electrodes. The resultant weld nugget formed is $$5$$ $$mm$$ in diameter and $$1.5$$ $$mm$$ thick. If the latent heat of fusion of steel is $$1400$$ $$kJ/kg$$ and the effective resistance in the welding operation is $$200\mu \Omega ,$$ the current passing through the electrodes is approximately

The figure below shows a graph, which qualitatively relates cutting speed and cost per piece produced.

The three curves $$1,2$$ and $$3$$ respectively represent

Two tools $$P$$ and $$Q$$ have signature $${5^ \circ } - {5^ \circ } - {6^ \circ } - {6^ \circ } - {8^ \circ } - {30^ \circ } - 0$$ and $${5^ \circ } - {5^ \circ } - {7^ \circ } - {7^ \circ } - {8^ \circ } - {15^ \circ } - 0$$ (both $$ASA$$) respectively. They are used to turn components under the same machining conditions. If $${h_p}$$ and $${h_Q}$$ denote the peak-to-valley height of surfaces produced by the tools $$P$$ and $$Q$$, the ratio $${h_P}/{h_Q}$$ will be

A $$600$$ $$mm$$ $$ \times \,\,30\,\,mm$$ flat surface of a plate is to be finish machined on a shaper. The plate has been fixed with the $$600$$ $$mm$$ side along the tool travel direction. If the tool over-travel at each end of the plate is $$20$$ $$mm,$$ average cutting speed is $$8$$ $$m/min,$$ feed rate is $$0.3$$ $$mm/stroke$$ and the ratio of return time to cutting time of the tool is $$1:2,$$ the time required for machining will be