815.6 A new concept: entropy Example 2: Find the entropy change of a system of two reservoirs when heat transfer g occurs from the warmer reservoir at temperature TH to the cooler reservoir at temperature Tc Solution: do Warmer reservoir: 4S Cooler reservoir: As rdo 2 Total entropy: AStotal TC H 815.6 A new concept: entropy placed in thermal contact with another mass m, at temperature Tc The system is isolated. so the heat transfer occurs only between the two masses. The final equilibrium temperature is T, where tc<r< Ty Find the total entropy change associated with the heat transfer between the hot and cold masses the specific heats of the masses are C, and c2 respectively Solution:AS、/d T/dT Q T =m, CaTH 1919 Example 2: Find the entropy change of a system of two reservoirs when heat transfer |Q| occurs from the warmer reservoir at temperature TH to the cooler reservoir at temperature TC. Solution: C f i H f i T Q T Q S T Q T Q S = = = = − ∫ ∫ d d ∆ Warmer reservoir: ∆ Cooler reservoir: Total entropy: 0 total = − > C TH Q T Q ∆S §15.6 A new concept: entropy Example 3: A mass m1 at temperature TH is placed in thermal contact with another mass m2 at temperature TC. The system is isolated, so the heat transfer occurs only between the two masses. The final equilibrium temperature is T, where TC < T < TH. Find the total entropy change associated with the heat transfer between the hot and cold masses.the specific heats of the masses are c1 and c2 respectively. Solution: H T T f i T T m c T T m c T Q S H ln d d ∆ 1 = ∫ = 1 1 ∫ = 1 1 §15.6 A new concept: entropy