reasons of calculate the energy absorb and the energy supply

1. heat loss to the surroundings
2. heat capacity of the cup, or other apparatus

3. efficiency of the heater(not 100% electricity is converted into heat)




4. you did not wait. it take time for the water to raise temp(evenly)


3 and 4 is not so good, 4 is the worst

i suggest you answer 1/2/3