One end of a thermally insulated copper rod of length 1 m long and of 10 cm^2 in cross-section is immersed in boiling water (100°C) and the other in ice (0°C). If KCu = 0.92 cal/cm/s/°C and Lice = 80 cal/g, the ice that will melt per minute is

Q: One end of a thermally insulated copper rod of length 1 m long and of 10 cm^2 in cross-section is immersed in boiling water (100°C) and the other in ice (0°C). If KCu = 0.92 cal/cm/s/°C and Lice = 80 cal/g, the ice that will melt per minute is

(a) 5.2 g

(b) 6.9 g

(c) 8.4 g

(d) 9. 2 g

Sol: (b)

Sol: $\large \frac{\Delta Q}{\Delta t} = \frac{K A \Delta T}{l}$

$\large \frac{m L_{ice}}{\Delta t} = \frac{K A \Delta T}{l}$

$\large \frac{m \times 80}{60} = \frac{0.92 \times 10 \times (100 -0) }{100}$

m = 6.9 g