A heat conducting rod, 1.1 m long, is made of an aluminum section that is 0.8 m
ID: 1489699 • Letter: A
Question
A heat conducting rod, 1.1 m long, is made of an aluminum section that is 0.8 m long, and a copper section that is 0.3 m long. Both sections have cross-sectional areas of 0.00040 m2. The aluminum end is maintained at a temperature of 40°C and the copper end is at 190°C. The thermal conductivity of aluminum is 205 W/m·K and of copper is 385 W/m·K. Steady state has been reached, and no heat is lost through the well-insulated sides of the rod. The temperature of the aluminum-copper junction in the rod is closest to how many degrees in Celcius?
A. 150
B. 160
C. 170
Explanation / Answer
[K*A*dT/l]Al = [K*A*dT/l]Cu
205*0.00040*(T-40)/0.8 = [385*0.00040*(190 - T)/0.3]
256.25*(T - 40) = (190 - T)*1283.33
256.25T - 10250 = 243832.7 - 1283.33T
10250 + 243832.7 = 1283.33T + 256.25T
254082.7 = 1539.58 T
T = 254082.7 / 1539.58
T = 165.03
Answer : Nearest Temperature = 160*C
OPTION B IS CORRECT
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