A jar of water is boiling under one atmosphere of pressure. Suppose that heat enters the jar only through its bottom, which is copper and rests on a heating element. In 2 minutes, the mass of water boiled away is m=3.5 kilogram. The radius of the jar bottom is R=6.5 centimeter and the thickness is L=2.0 millimeter. Find the temperature of the heating element in contact with the jar?