In certain machining operation with a cutting speed of $$50$$ $$m/min,$$ tool life of $$45$$ minutes was observed, when the cutting speed was increased to $$100$$ $$m/min,$$ the tool life decreased to $$10$$ minutes. The cutting speed for maximum productivity, if tool change time is $$2$$ minutes is

In Whitworth quick return mechanism (used in shapers) the velocity of the $$ram$$ is maximum at

For $$50\% $$ penetration of work material, a punch with single shear equal to thickness will