6. Leo, Yu, and Colleen place 500 ml of hot coffee at 80 .C is in a closed Styrofoam cup which is 5.0 mm thick and has a surface area of 370 cm2. The day is windy and the air outside the cup remains at a constant temperature of 20C. The thermal conductivity of Styrofoam is k = 5.5 x 10 6 kcal/s m C. Assume that 500 ml of coffee has a mass of 0.50 kg, and that specific heat of coffee is the same as that of water, Ccoffee = 1.0 kcal/kg .C Determine the: a. initial rate of heat flow through the Styrofoam (10 points) b. time required for the temperature of the coffee to cool from 80C to 70 C (10 pts)