physics.f.3 about temperature

2.if the kinetic energy increase, the temp. will increase, If reach the boiling point, them a body's K.E AND P.E increase, the body will change in state.

3.NO, although the temp.(K.E) is higher than y, there is also Potential energy. if the potential energy is also higher than y, you can say that x have more internal energy than y. IF NOT, you can't

2010-10-16 21:44:54 補充：
如果你本身math 吾好, 吾好chose phy. 但係chem 一定要, 因為大學好多科都要有讀chem. 其實最好ge ofcourse 3科修晒

1. The internal energy of a body is the kinetic energy and potential energy (due to intermolecular force) possessed by its molecules. Temperature is the degree of "hotness" of the body.

The degree of hotness, or temperature, of a body is the macroscopic manifestation on the amount of kinetic energy possessed by the molecules.[Note: the potential energy of molecules is macroscopically manifested by the "volume" of the object. Hence, an increase in potential energy, and thus increase in separations, of molecules on heating is observed as expansion of the object.]

2. The statement is not true.

The average kinetic energy of a molecule in body X is larger than that in body Y if the temperature of X is higher than that of Y. However, it is not necessary that the average potential energy of a molecule in body X is larger than that in Y Hence, it may not be true that the internal energy (which is the sum of kinetic and potential energies) of body X is larger than that of body Y if body X is at a higher temperature.
The number of molecules also accounts for the internal energy. If body Y contains more molecules than body X, then the total energy (internal energy) possessed by all molecules in body Y may exceed the total energy possessed by molecules in body X, which are fewer in number, even if the temperature of X is higher than that of Y.