Transmission Of Heat Question 194
Question: A cup of tea cools from 65.5o C to 62.5 o C in one minute in a room of 22.5 o C. How long will the same cup of tea take, in………….. minutes, to cool from 46.50 o C to 40.5 o C in the same room ? (choose nearest value)
[Kerala PMT 2004]
Options:
A) 1
B) 2
C) 3
D) 4
Show Answer
Answer:
Correct Answer: D
Solution:
$ \frac{65.5-62.5}{1}=K( \frac{65.5+62.5}{2}-22.5 ) $
Therefore $ K=\frac{3}{41.5} $ And again $ \frac{46.5-40.5}{t}=\frac{3}{41.5}( \frac{46.5+40.5}{2}-22.5 ) $
Therefore $ \frac{6}{t}=\frac{3}{41.5}\times 21 $
Therefore $ t=\frac{82}{21}\tilde{-}4 $ minute.
BETA
