另外為什麼一座冰山的內能比一杯熱水更高?
冰山又不是熱.......
更新1:
我還是不太明白 冰山不是十分冷的嗎 為什麼將它壓縮成一杯水就會變得熱?
「熱 」 與 「 內能 」 有分別嗎? 急!!!!
回答 (2)
2010-01-21 1:49 am
✔ 最佳答案
分別就好少,我都唔係好識講因為一座冰山係好大,同好重
起碼都300kg啦
1杯水通常都係得1kg
因為係中3會教
e= mc delta t
係一條公式黎
c係比熱容量(每1公斤物質上升一度所需既能量)
m就係重量
冰既比熱容量係2100
水係4200
噤你300kg比1kg緊係大得多啦
100x2100都630000啦
你水最多都係100度
1x100x4200都係420000
2010-01-20 5:17 am
You probably have mixed up "internal energy"(內能) and "temperature".(溫度). They are completely different physical quantities.
The "internal energy" is the energy possessed by an object because of the kinetic energy (KE) and potential energy (PE) of its molecules. It is the KE of molecules gives rise to the :temperature" of the object. The higher the KE of molecules, the higher is the temperature.
Objects of different size or mass contain different number of molecules. Hence, the "internal energy" of an object is, in fact, the total KE and PE of ALL of its molecules.
Suppose an object (object A) contains N molecules and each molecule possesses a sum of KE & PE equal to [e] on average. The "internal energy"possessed by this objject = N.[e].
If another object (object B) has much less number of molecules, say n, but each molecule possesses higher KE & PE, say, equal to energy [E]. This object will have a higher temperature than object A, because each of its molecules has higher energy than those in object A, i.e. [E] > [e] The "internal energy" of object B is thus equal to n.[E].
Therefore, depending on the actual value of n and N, though [E] > [e], the quantity N.[e] may not be smaller than n.[E], if N >> n
An iceberg contains water molecules billion times more than water molecules in a cup of hot water. Although the energy possessed by a molecule in the hot water is higher than a molecules in an iceberg (e.g. if the water is at 100'C and the iceberg is at 0'C, the energy of a molecule in water is about 100 times the energy in a molecule in the iceberg, that's why the hot water feels hotter than the iceberg). However, there are, suppose, a billion (1,000,000,000) molecules in the iceberg. The sum of energy possessed by all these billion molecules (internal energy) is surely much higher than the total energy possessed by the small number of molecules in the hot water.
The "internal energy" is the energy possessed by an object because of the kinetic energy (KE) and potential energy (PE) of its molecules. It is the KE of molecules gives rise to the :temperature" of the object. The higher the KE of molecules, the higher is the temperature.
Objects of different size or mass contain different number of molecules. Hence, the "internal energy" of an object is, in fact, the total KE and PE of ALL of its molecules.
Suppose an object (object A) contains N molecules and each molecule possesses a sum of KE & PE equal to [e] on average. The "internal energy"possessed by this objject = N.[e].
If another object (object B) has much less number of molecules, say n, but each molecule possesses higher KE & PE, say, equal to energy [E]. This object will have a higher temperature than object A, because each of its molecules has higher energy than those in object A, i.e. [E] > [e] The "internal energy" of object B is thus equal to n.[E].
Therefore, depending on the actual value of n and N, though [E] > [e], the quantity N.[e] may not be smaller than n.[E], if N >> n
An iceberg contains water molecules billion times more than water molecules in a cup of hot water. Although the energy possessed by a molecule in the hot water is higher than a molecules in an iceberg (e.g. if the water is at 100'C and the iceberg is at 0'C, the energy of a molecule in water is about 100 times the energy in a molecule in the iceberg, that's why the hot water feels hotter than the iceberg). However, there are, suppose, a billion (1,000,000,000) molecules in the iceberg. The sum of energy possessed by all these billion molecules (internal energy) is surely much higher than the total energy possessed by the small number of molecules in the hot water.
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