a portion of an electirc circuit connected toa 40-ohm resistor is embedded in .2 kg of a solid substance in a calorimeter. The externam portion of the circuit is connected to a 60 V power supply. At 80 C the substance begins to melt. The heat of fusion of the substance is 1.35*10^5 J/kg. How long after the temperature reaches 80 C will it take to melt all of the substance? I really don't understand how to find time. I get that there's a way to find heat of fusion, but it's already given to me. help plz i have originally posted this in the advanced physics but no one helped. maybe someone here will.