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morrobay
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Homework Statement
Two 100g Aluminum cubes with T1 = 80° C and T2 = 20°C
Specific heat of Al is .22 cal/g/°C. The cubes are placed in contact and in short period of time
a quantity of heat, dQ , is transferred from T1 cube to T2 cube.
The cubes temperatures now are 75°C and 25°C. After a little math : dQ = 640 Joules
The total entropy of the two cubes before dQ was: 22.3 J/K and after dQ was 27.5 J/K
Homework Equations
S2-S1 > ∫12 dQ/T
ΔS = 5.2 J/K > ∫12 dQ/T This should be evaluated :
ln dQ/T - ln dQ/T . The question on this is what are the T values here ?
Is it necessary to do two evaluations, one for hotter object and another for cooler object ?
,
The Attempt at a Solution
S2-S1 = 5.2J/K
For hotter object ln 460 J/348K - ln 460J/353K = .01
For cooler object ln 460J/293K - ln 460J/298K = .02