Transmission Of Heat Question 120
Question: A 5cm thick ice block is there on the surface of water in a lake. The temperature of air is ?10°C; how much time it will take to double the thickness of the block (L = 80 cal/g, Kicc = 0.004 Erg/s-k, dice = 0.92 g cm?3)
[RPET 1998]
Options:
A) 1 hour
B) 191 hours
C) 19.1 hours
D) 1.91 hours
Show Answer
Answer:
Correct Answer: C
Solution:
$ t=\frac{Ql}{KA({\theta _{1}}-{\theta _{2}})}=\frac{mLl}{KA({\theta _{1}}-{\theta _{2}})}=\frac{V\rho Ll}{KA({\theta _{1}}-{\theta _{2}})} $
$ =\frac{5\times A\times 0.92\times 80\times \frac{5+10}{2}}{0.004\times A\times 10\times 3600}=19.1,hours $ .
BETA
