F.4 Phy 問題... (10點)

if you are understand the concept, it is actually very easy to get that the answer is 45 x 2 =90mins.
Since the specific heat capacity of water is 2 times of oil. Specific heat capacity mean the Energy need to increase the temperature of 1kg of object for 1C. Since the temperature change, mass and energy provided by the radiator are the same, the time is proportional to the specific heat capacity.
Do you understand the concept?

2007-02-04 02:24:46 補充：
sorry a bit mistake is that energy provided per hour is the same. specific heat capacity proportional to the total energy provided. total energy provided proportional to total time.(i.e. E=Pt, P is the same)

2007-02-04 02:24:57 補充：
Here is the formular:Energy= specific heat capacity * mass * temperature changePower * time =specific heat capacity * mass * temperature changePower, mass and temperature change are the same for two radiators, so time proportional to specific heat capacity.

2007-02-04 13:55:21 補充：
it take 90mins to reach 60C so it is 45mins longer than that of oil filled radiator to reach 60C.

水的heat capacity是油的2倍，假設暖爐的輸出功率相同，則將水加熱到與油同一特定溫度所需的時間，等於油所需的2倍。

加熱水至60度需時：45分鐘 x 2 = 90分鐘