10 kg piece of aluminum, initially at 300 k, is melted and used in the casting process. the heating and melting process is divided into two steps. in the first step the piece of aluminum is heated by hot air at 400˚c until its temperature rises to 600 k. then in the second step its temperature increases to 900 k by heating by hot exhaust gas at 1400 k. find the entropy generated in this process. properties of aluminum are the following: density and specific heat of liquid and solid phase: 2700 kg/m3 and 1040 j/kg, latent heat of fusion 321 kj/kg and melting temperature 883 k.