In casting experiments performed using a certain alloy and type of sand mold, it took 250 sec for a cube shaped casting to solidify. The cube was 50 mm on a side. Determine the value of the mold constant in Chvorinov's rule.

On solidification from a melt, the polymer polyethylene forms a semi-crystalline spherulite structure. (i) sketch an individual spherulite and label the amorphous and crystalline regions. (ii) draw a schematic to show the changes in specific volume with temperature during cooling from the melt, comparing it to the theoretical extremes of fully crystalline and fully amorphous (indicate tm and tg)