A liquid in a beaker is at an initial temperature of 15 C. The beaker is placed on a magnetic stirring plate as shown in the figure. The objective is to increase the temperature of the liquid to 55 C. When the plate is turned on, the stirring of the liquid is enough to keep its temperature uniform at all times. During the process, the plate continuously provides 100 W of thermal energy to the bottom of the beaker. Convection to the surrounding air at 15 C takes place from the side of the beaker with hi = 12 W/mK, and from the top surface of the liquid with h2 = 30 W/mK. Neglecting the heat transfer resistance of the beaker's glass wall, determine the time necessary for the liquid to reach 55 C. Liquid properties: k = 0.6 W/mK, p = 1000 kg/m?, Cp = 4200 J/kg K. J Now consider the heat transfer resistance of the glass walls: The walls are 7 mm thick and the glass has thermal conductivity k=0.2 W/m K. Determine the time necessary for the liquid to reach 55 C