物理題(熱容量+能量轉換)非常緊急

1. You need to introduce a term to account for the "heat lost to the surroundings" when writing your "heat balance equation".

Hence, Q + Hs = S
where Q is the heat gain by the substance of interest
S is the heat supplied
Hs is the heat lost to the surroundings.

Writing Q = mcT
where m is the mass of substance of interest
c is its specific heat capacity
T is the rise in temperature

Thus, c = (S - Hs)/mT
Clearly, if the term Hs is ignored (i.e. setting Hs = 0), the value of c so found (experimental value) is larger than the true value (value that Hs is not zero).

On the other hand, suppose in the experiment, the substance under test is giving out heat (i.e. there is a fall in temperature) instead of gaining heat, the heat balance equation becomes,

Q = S' + Hs
where S' is the heat absorbed by a heat-sink
Thus, mcT' = S' + Hs
where T' is the fall in temperature of the substance under test
c = (S' + Hs)/mT'
Therefore, if the term Hs is ignored (i.e. setting Hs = 0), the value of c so found (experimental value) is smaller than the true value (value that Hs is not zero).

You could apply the above two situations suitably to any specific experiments.

2. When there is (i) a rise in temperature; or (ii) a change of state from solid to liquid or from liquid to gas, the potential energy of molecules in a substance increases.

Total potnetial energy PE(total) is not the same as average potential energy PE(average). They are related by the following equation:

PE(total) = PE(average) x no. of molecules in a substance