A falk consisting of a cope and drag has the following dimensions: length $$300mm,$$ width $$200mm,$$ and total septh $$200mm$$ (cope height $$50mm$$).
A $$150mm\,\, \times \,100mm\,\, \times 50mm$$ cast iron block is to be cast. If the specific weight of cast iron is $$78\,\,kN/{m^3}$$ and that of the mold sand $$16\,\,kN/{m^3}$$, find lifting force on the cope created by buoyant force, weight of sand in the cope, the net force at the liquid-sand interface and additional weight to be kept on the cope.