Two copper blocks, each of mass 1.90 kg, initially have different temperatures,t1 = 21° C and t2 = 32° C. The blocks are placed in contact with each other and come to thermal equilibrium. No heat is lost to the surroundings.
(a) Find the final temperature of the blocks.
Find the heat transferred between them.
(b) Find the entropy change of each block during the time interval in which the first joule of heat flows.
(c) Estimate the entropy change of each block after it has reached thermal equilibrium. Use each block's average temperature during the process in calculating the estimated values of ΔS.
- oubaasLv 710 months agoFavorite Answer
The surplus of energy stored in the hotter body is received by the other , so that while one decreases its own temperature, the other increases by the same amount, being the two bodies equal in mass and material .
ΔE = m*c*ΔT/2 = 1.90*385*(32-21)/2 = 4,023 joule
more in details :
Total energy E = m*c*T1+m*c*T2 = m*c*(T1+T2)
Te = E/(2*m*c) = m*c*(T1+T2)/(2*m*c) = (T1+T2)/2 = 53/2 = 26.5°C
ΔE = m*c*(Te-T1) = 1.90*385*(26.5-21) = 4,023 joule (acquired energy)
ΔE = m*c*(T2-Te) = 1.90*385*(32-26.5) = 4,023 joule (released energy)