A machine element has an ultimate strength $$\left( {{\sigma _u}} \right)$$ of $$600\,\,N/m{m^2},$$ and endurance limit $$250$$ $$\,N/m{m^2}.$$ The fatigue curve for the element on log-log plot is shown below. If the element is to be designed for a finite of $$10000$$ cycles, the maximum amplitude of a completely reversed operating stress is _________ $$\,N/m{m^2}.$$

A sprue in a sand mould has a top diameter of $$20mm$$ and height of $$200mm.$$ The velocity of the molten metal at the entry of the sprue is $$0.5m/s.$$ Assume acceleration due to gravity as $$9.8\,\,m/{s^2}$$ and neglect all losses. If the mould is well ventilated, the velocity (upto $$3$$ decimal points accuracy) of the molten metal at the bottom of the sprue is ______________________ $$m/s.$$

In a metal forming operation when the material has just started yielding, the principal stresses are $${\sigma _1} = \,\, + 180\,\,MPa,\,\,\,$$ $${\sigma _2} = \,\, - 100\,\,MPa,\,\,\,$$ $${\sigma _3} = 0.$$ Following Von Mises' criterion, the yield stress is _____________ $$MPa.$$

In an arc welding process, welding speed is doubled. Assuming all other process parameters to be constant, the cross sectional area of the weld bead will