A body cools from a temperature 3T to 2T in 10 minutes. The room temperature is T. Assume that Newton's law of cooling is applicable. The temperature of the body at the end of next 10 minutes will be
- 74 T
- 32 T
- 43 T
- T
Answer
(2) 32 T
Solution
As per NCERT, Newton's law of cooling (average form): 1 - 2t = k ( 1 + 22 - 0 )
First 10 min: 3T - 2T10 = k ( 5T2 - T )
T10 = k 3T2 k = 115
Next 10 min (final temperature ): 2T - 10 = 115 ( 2T + 2 - T )
2T - = 3
4 3 = 2T
= 32 T
Answer: (2)