7-88 An insulated piston-cylinder device initially contains 300 L of air at 120 kPa and 17°C. Air is now heated for 15 min by a 200-W resistance heater placed inside the cylin- der. The pressure of air is maintained constant during this process. Determine the entropy change of air, assuming (a) constant specific heats and (b) variable specific heats.

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Insulated water tank Water (0.12m) COPPER A 50-kg copper block initially at 80°C is dropped into an insulated tank that contains 0.120 m3 of water at 25FC. Determine the final equilibrium temperature and the total entropy change for this process. Properties: Take the density and specific heat of water as p=997 kg/m3 and cp-4.18KJ/kgK, respectively. and the specific heat of copper as cp=0.386KJ/kgK (values at room temperature). OA0 204 kJk O0035 kJikgK