熱容量同比熱容量既問題

Without referring to their definitions, heat capacity is used on an object (e.g. a block, a cup, a tank etc), whereas specific heat capacity is used on a material, eg. water, copper etc.

The two physical quantities are related by the following equation:

Heat capacity = (mass of object) x (specific heat capacity of material of object)

Thus, the unit for "heat capacity" is J/C, i.e. the amount of heat energy required to raise the temperature of an object by 1'C. The unit for "specific heat capacity" is J/kg-C, i.e. the amount of energy required to raise the temperature of unit mass (1 kg) of the material by 1'C.

For example, copper has a specific heat capacity of 390 J/kg-C. That is to say, it needs 390 J of heat to raise 1 kg of copper by 1'C. Notice that we are talking about the material "copper".

However, if a cup made of copper has a mass of, say 100g (=0.1 kg). Then the heat capacity for this particular copper cup is 0.1 x 390 J/C = 39 J/C. The heat capacity indicates that it requires 39 J of heat energy to raise the temperature of the cup by 1'C. Notice that we are now talking about the object "cup".

If another copper cup of mass 150g (=0.15 kg) is used, then its heat capacity is 58.5 J/C (= 0.15 x 390 J/C). This means that 58.5 J of energy is needed to raise the temperature of this heavier cup by 1'C. Notice that both of the two objects (the cups) are of material copper, but they have different "heat capacity" becuase of their masses are different.