Solution: (a)In the equivalent reversible process △Emt=Q+W=Q=mC,△7+m,C(44) In the original irreversible process, we have AEint=Q+w=w=mgh=110J From AEn+= AEin(internal energy is a state quantity) →>△T mgh =5.5mK C+mc f do rf m cdT+m cdT (b)△S m.C.△T+mC△T110J =0.37J/K△S>0 300K (c)In the reverse process, 0=-110J AS=-0.37J/K, AS<Onever happen
Solution: (a) In the equivalent reversible process (24-4) In the original irreversible process, we have Eint = Q +W = Q = mw Cw T + ms Cs T E Q W W m gh J ' int = + = = s =110 mK m C m C m gh T w w s s s = 5.5 + = (b) + = = f i w w s s f i T m C dT m C dT T dQ S S 0 (c) In the reverse process, , , it never happen. Q = −110J S = −0.37J / K S 0 (internal energy is a state quantity) int int From E = E' J K K J T mw Cw T ms Cs T 0.37 / 300 110 = = +
Sample problem 24-3 Insulation. Fig 24-3 shows a paper hot cold cup containing a mass m=0.57kg of hot water and H a similar cup containing an equal mass of cold water Fig 24-3 The initial temperature of Insulation the hot water is Tu=363K that of the cold water is Tc=283K. H Fig 24
Sample problem 24-3 Fig 24-3 shows a paper cup containing a mass m=0.57kg of hot water and a similar cup containing an equal mass of cold water. The initial temperature of the hot water is ; that of the cold water is . hot cold H C Fig 24-3 TiH = 363K TiC = 283K H C Fig 24-4 Insulation Insulation
When the insulating shutter separating the two enclosure is removed, the hot water and the cold water eventually come to thermal equilibrium at a temperature of T=323K What is the entropy change of the system for this irreversible process?(Cw=4190 /kg. k, the heat capacity of the paper cups is negligible)
When the insulating shutter separating the two enclosure is removed, the hot water and the cold water eventually come to thermal equilibrium at a temperature of . What is the entropy change of the system for this irreversible process? ( , the heat capacity of the paper cups is negligible) Tf = 323K kg K C J w = 4190