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JEE Main202127 Jul 2021Morning ShiftPhysicsThermal Properties of MatterActual

A body takes 4 min to cool from 61 ° C to 59 ° C . If the temperature of the surroundings is 30 ° C , the time taken by the body to cool from 51 ° C to 49 ° C is:

Options

  1. A4   min .
  2. B3   min .
  3. C8   min .
  4. D6   min .

Correct answer

D. 6   min .

Step-by-step solution

Δ T Δ t = K T t - T S   T t = average temperature T S = surrounding temperature 61 - 59 4 = K 61 + 59 2 - 30   . . . ( i ) 51 - 49 t = K 51 + 49 2 - 30     . . . ii Divide ( 1 ) and ( 2 ) t 4 = 60 - 30 50 - 30 = 30 20 So, t = 6 min

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