物理Q 2條

1. The 0.2 kg of ice would cool better than the 1 kg vessel does.
A large amount of heat is absorbed when the ice undergoes a change of state, from ice to water. For 0.2 kg of ice at 0'C, the heat absorbed equals to 0.2 x 334 kJ = 66.8 kJ

2. In the cooling chanber, the liquid refrigerant (雪種) is under a pressure reduction process (減壓過程). Hence, this accelerates the evaporation rate.


2013-11-27 23:07:23 補充：
Some amendment to Q1:
The 1st sentence of the 2nd para. should read "A large amount of heat is absorbed when the ice undergoes a change of state, from ice to water, WITHOUT A CHANGE OF TEMPERATURE".

2013-11-29 08:08:43 補充：
Your suppl questions:
1. When ice melts, it absorbs heat and there is NO increase of temperature (this point is very very important). But when the 1 kg vessel absorbs heat, its temperature will rise. The mass difference is not so important.

2013-11-29 08:11:53 補充：
2. It is just a matter of the unit used. I used 335 kJ/kg as the latent heat of fusion, which is just 3.35 x 10^5 J/kg.