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Concepts Of Physics MCQ Edition [Volume 2]PhysicsHeat Transfer

A body requires 5 minutes to cool from 65^ C to 60^ C . To cool from 60^ C to 55^ C , it will take

Options

  1. Aless than 5 minutes
  2. B5 minutes
  3. Cmore than 5 minutes
  4. Deither less or more than 5 minutes, depending on whether its mass is greater or less than 1 kg

Correct answer

C. more than 5 minutes

Step-by-step solution

According to Newton's law of cooling, the rate of fall of temperature is given by T t = k(T_ avg - T₀) For the first case: 65 - 60 5 = k ( 65 + 60 2 - T₀ ) 1 = k(62.5 - T₀) For the second case, let the time taken be t : 60 - 55 t = k ( 60 + 55 2 - T₀ ) 5 t = k(57.5 - T₀) Since 57.5 - T₀ Thus, 5 t 5 minutes .

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