Transmission Of Heat Question 320
Question: A body cools down from $ 70^{o}C $ to $ 60^{o} $ in 5 min. It will cool down from $ 100^{o}C $ to $ 90^{o}C $ in (Assume cooling by radiation alone)
Options:
A) More than 5 min
B) less than 5 min
C) 5 min
D) Can’t be computed from information provided
Show Answer
Answer:
Correct Answer: B
Solution:
[b] As the body is cooling through radiation, so rate of cooling is proportional to fourth power of its absolute temperature. So rate of cooling is more when temperature is more, hence it takes less time to cool from $ 100^{o}C $ to $ ~90^{o}C $ as compared to when body cools from $ 70^{o}C $ to $ 80^{o}C $ .
BETA
