A ‘thermacole’ icebox is a cheap and efficient method for storing small quantities of

cooked food in summer in particular. A cubical icebox of side 30 cm has a thickness of

5.0 cm. If 4.0 kg of ice is put in the box, what is the amount of ice remaining after 6 h?

The outside temperature is 45 °C, and the coefficient of thermal conductivity of thermacole is 0.01 J s-1 m-1 K-1.Heat of fusion of water=335×103 J kg-1

1. 2.9 kg
2. 3.1 kg
3. 3.7 kg
4 4.10 kg

Subtopic:  Conduction |
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A brass boiler has a base area of 0.15 m2 and a thickness of 1.0 cm. It boils water at a rate of 6.0 kg/min when placed on a gas stove. What is the temperature of the part of the flame in contact with the boiler?
(Thermal conductivity of brass = 109 J s-1 m-1 K-1, the heat of vaporization of water =2256×103 J/kg.)
1. 237.98°C
2. 150°C
3. 137.98°C
4. 100°C

Subtopic:  Conduction |
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