A Cup of Coffee Is Enclosed on All Sides in an Insulated

Multiple Choice

A cup of coffee is enclosed on all sides in an insulated container 1/2 cm thick in the shape of a cube 10 cm on a side.The temperature of the coffee is 95 $\degree$ C,and the temperature of the surroundings is 21 $\degree$ C.Find the rate of heat loss (in J/s) due to conduction if the thermal conductivity of the cup is 2 *10 ^{- 4} cal/s.cm. $\degree$ C.

A) 62
B) 74
C) 230
D) 160
E) 12