A portion of an electric circuit connected to a 40 ohm resistor is embedded in 0.20 kg of a solid substance in a calorimeter. The external portion of the circuit is connected to a 60 volt power supply.
(a) Calculate the current in the resistor.
(b) Calculate the rate at which heat is generated in the resistor.
(c) Assuming that all the heat generated by the resistor is absorbed by the solid substance, and that it takes 4 minutes to raise the temperature from 20to 80 degrees C, calculate the specific heat for the substance.
(d) At 80 degrees C, the substance begins to melt. The heat of fusion is 1.35 x 10^5 joules per kilogram. How long after the temperature reaches 80 degrees C will it take for all of the substance to melt?