Question

An ice box used for keeping eatables cool has a total wall area of 1 metre² and a wall thickness of 5.0 cm. The thermal conductivity of the ice box is K= 0.01 J/m^0C. It is filled with ice at 0^0C along with eatables on a day when the temperature is 30^0C. The latent heat of fusion of ice is 334×10³ J/kg. The amount of ice melted in one day is (1 day = 86,400 seconds)

• A. 776 g
• B. 7760 g
• C. 11520 g
• D. 1552 g

Answer 1

Answer: (D)

1552 g

Answer 2

Quantity of heat transferred through wall will be utilized in

melting of ice.

$Q = \frac{KA\Delta\theta t}{\Delta x} = mL$ ∴ Amount of ice melted $m = \frac{KA\Delta\theta t}{\Delta xL}$

∴ $m = \frac{0.01 \times 1 \times (30 - 0) \times 86400}{5 \times 10^{- 2} \times 334 \times 10^{3}} = 1.552kg$ or 1552g