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Concepts Of Physics MCQ Edition [Volume 2]PhysicsHeat Transfer

Consider the situation depicted in the figure. The frame is constructed from the same material and possesses a uniform cross-sectional area throughout. Determine the amount of heat flowing per second through a cross section of the bent part, given that the total heat extracted per second from the end at 100^ C is 130 J .

Options

  1. A70 J
  2. B60 J
  3. C130 J
  4. D65 J

Correct answer

B. 60 J

Step-by-step solution

The thermal circuit consists of a parallel combination of the straight middle part and the bent part, connected in series with the two end parts. The length of the straight middle part is L₁ = 60 cm . The length of the bent part is L₂ = 5 cm + 60 cm + 5 cm = 70 cm . Since the frame is made of the same material and has a uniform cross-sectional area, the thermal resistance R of any part is proportional to its length L ( R = L KA ). Let the thermal resistance of the straight part be R₁ = 60k and that of the bent part

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