A 2 kg sample of air contained in a 2 m3 rigid container undergoes a process in which its pressure reduces from 100.45 kPa to 86.10 kPa while the volume remains the same. Please calculate (a) how much work was done, (b) by how much did the internal energy of the air change, (c) how much heat was transferred (please specify the direction of heat transfer).

Total solidification times of three casting geometries are to be compared: a sphere, a cylinder, in which the length-to-diameter ration - 1.0, and a cube. volume = 1000 cm^3 for all three shhapes, and the same casting alloy is used. a) determine the solidification times of each geometry b) based on the results of part (a), which geometric element would make the best riser? c) if the mold constant = 3.5 min/cm^2 in chvorinov's rule, compute the total solidification time for each casting.