A wooden box having dimensions 80 cm x 60 cm x 30 cm and thickness 3 cm contains ice. What will be the rate of melting of ice if external temperature is 30^@Cand coefficient of thermal conductivity is 0.176 Wm^(-1) K^(-1)and latent heat of ice = 80 cal/g.

A wooden box having dimensions 80 cm x 60 cm x 30 cm and thickness 3 c

1.	A wooden box having dimensions 80 cm x 60 cm x 30 cm and thickness 3 cm contains ice. What will be the rate of melting of ice if external temperature is 30^@Cand coefficient of thermal conductivity is 0.176 Wm^(-1) K^(-1)and latent heat of ice = 80 cal/g.
Answer» Solution :`DELTA x = 3 cm = 3 xx 10^(-2) m` Area ` = 2[ (80 xx 60) + 60 xx 30) + (30 xx 80) ] cm^2` ` = 2(4800 + 1800 + 2400) cm^2 = 1.8m^2` `Delta T = 30^@C` ` K = 0.176 Wm^(-1) K^(-1)` ` = 0.04 cal m^(-1) K^(-1)` m = mass of ice MELTED `(dQ)/(dt) = mL = KA (Delta T)/(Delta x)` ` RARR m = (KA Delta T)/(Delta x L) = (0.04 xx 1.8 xx 30)/(3 xx 10^(-2) xx 80) = 0.9 g `