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Mechanical Engineering QUESTION #2421
Question 1
For a composite plane wall with convection on both sides, the total thermal resistance is:
  • \(R_{total} = h_1 A + \sum R_i + h_2 A\)
  • \(R_{total} = \frac{1}{h_1 A} + \sum\frac{L_i}{k_i A} + \frac{1}{h_2 A}\)✔️
  • \(R_{total} = \frac{1}{h_1 h_2 A^2}\)
  • \(R_{total} = \frac{k_1+k_2}{A(h_1+h_2)}\)
Correct Answer Explanation
For a composite wall with convection on both sides, all resistances are in series: \(R_{total}=\frac{1}{h_1A}+\frac{L_1}{k_1A}+\frac{L_2}{k_2A}+\cdots+\frac{1}{h_2A}\).