Two mozzarella cheese cubes of sides 0.8 and 0.4 cm are initially at 20 °C. Physical properties of mozzarella are: = 1050 kg/m3, Cp = 2800 J/kg K, melting point: Tm = 55 °C. We will assume that internal resistance to heat transfer is negligible in the cubes. (a) If both cheese cubes are placed in a conventional oven at a temperature of 100 °C with convective heat transfer coefficient h = 50 W/m²K, calculate the time at which the cheese will begin to melt for both cubes. Which cube melts first? Assume that the side on which the cube rests is insulated, so that convection takes place from 5 of the cube's 6 faces. (b) If the cubes are placed in a microwave oven at a temperature of 20 °C with the same heat transfer coefficient as in part (a) acting on 5 faces, and with a uniform thermal energy liberation due to microwave heating Er= 2.8 W/cm", calculate the time at which the cheese will begin to melt for both cubes. Which cube melts first?