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A black body of mass 34.38 g and surface area 19.2 c m 2 is at an initial temperature of 400 K . It is allowed to cool inside an evacuated enclosure kept at constant temperature of 300 K . The rate of cooling is 0.04 o C/s . The specific heat of body is

Options

  1. A2800 J/k g-K
  2. B2100 J/k g-K
  3. C1400 J/k g-K
  4. D1200 J/k g-K

Correct answer

C. 1400 J/k g-K

Step-by-step solution

From stefan's law, m c d T d t = σ T 4 - T 0 4 A ⇒ c = σ T 4 - T 0 4 A m d T d t = 5.67 × 10 - 8 400 4 - 300 4 × 19.2 × 10 - 4 34.38 × 10 - 3 × 0.04 ⇒ c = 1400 J/k g-K

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