For butt welding $$40mm$$ thick steel plates, when the expected quantity of such jobs is $$5000$$ per month over a period of $$10$$ years, choose the best suitable welding process out of the following available alternatives.

In a particular mold design, the down sprue has an area of Cross section of $$6.45\,\,c{m^2}$$ where the pouring basin leads into the sprue. The sprue is $$20$$ $$cm$$ long. The required metal flow rate at the top section of the sprue is $$820$$ $$c{m^3}/s.$$ Determine the pouring height necessary above the sprue top. Also determine the area of $$C.S$$ of sprue at its bottom to avoid the aspiration of liquid molten metal.

Which of the following materials requires the largest shrinkage allowance, while making a pattern for casting?

Consider the system of two wagons shown in Figure. The natural frequencies of this system are