Transmission Of Heat Question 182
Question: A body cools from $ {{50.0}^{o}}C $ to $ {{49.9}^{o}}C $ in $ 5\ s $ . How long will it take to cool from $ {{40.0}^{o}}C $ to $ {{39.9}^{o}}C $ ? Assume the temperature of surroundings to be $ {{30.0}^{o}}C $ and Newton’s law of cooling to be valid
[CBSE PMT 1994]
Options:
A) 2.5 s
B) 10 s
C) 20 s
D) 5 s
Show Answer
Answer:
Correct Answer: B
Solution:
$ \frac{50-49.9}{5}=K,( \frac{50+49.9}{2}-30 ) $ ?..(i) $ \frac{40-39.9}{t}=K,[ \frac{40+39.9}{2}-30 ] $ ?..(ii) from equations (i) and (ii) we get t » 10 sec.
BETA
