A 2.0-m' Thermopane window is constructed, using two layers of glass 4.0 mm thick, separated by an air space of 5.0 mm. If the temperature difference is 20 C" from the inside ofthe house to the outside air, what is the rate of heat flow through this window? (Thermal conductivity for glass is 0.84 J/smC and for air 0.023 4 J/sm C.) (180 W) I place a 500-g ice cube (initially at 0'C) in a Styrofoam box with wall thickness 1.0 em and total surface area 600 cm . If the air surrounding the box is at 20"C and after 4 hours the ice is completely melted, what is the conductivity of the Styrofoam material? (ly= 80 cal/g) (2.3 x 10 4 cal/scm C) What is the temperature increase of 4.0 kg of water when heated by an 800-W immersion heater for 10 min? (cw = 4 186 J/kg'C) (29'C) A waterfall is 145 m high. What is the increase in water temperature at the bottom of the falls if all the initial potential energy goes into heating the water? (g = 9.8 m/s), CW =4 186 J/kg'C) (0.34'C) A solar heated house loses about 5.4 x 10' cal through its outer surfaces on a typical 24-h winter day. What mass of storage rock is needed to provide this amount of heat if it is brought up to initial temperature of 62"C by the solar collectors and the house is maintained at 20'C? (Specific heat of rock is 0.21 cal/g.C.) (6 100 kg)