Chapter 16, Problem 51PCE

Predict/Explain Two identical bowls of casserole need to be kept warm. The cook covers bowl 1 with transparent plastic wrap and bowl 2 with shiny aluminum foil, in each case trapping a layer of air between the covering and the casserole. (a) After a few minutes, will the temperature of casserole 1 be greater than, less than, or equal to the temperature of casserole 2? (b) Choose the best explanation from among the following:

1. I.            The lower thermal conductivity of the plastic wrap over casserole 1 will suppress heat loss by conduction better than aluminum foil.
2. II.            In each case heat loss by convection is suppressed so the final temperatures will be the same.
3. III.            The high reflectivity of the aluminum foil over casserole 2 will suppress heat loss by radiation, while the heat losses by conduction and convection for casseroles 1 and 2 will be similar.