Specific Heat
INTRODUCTION Whenever two objects with different initial temperatures are put in contact with each other, the warmer one will cool down, and the cooler one will warm up, until they reach the same temperature. We now know that this has to do with the motions of molecules: what we sense as temperature is related to the average kinetic energy of the molecules of each material: the faster they’re vibrating around, the hotter the object feels. We can sidestep this molecular picture by dealing with objects as a whole, and treating the energy transfer as the flow of heat, rather than kinetic energy transfer among particles.
|Specific Heat for Various Materials |
|Material |Specific Heat |
| |(J/kg C°) |
|Water |4186 |
|Aluminum |900 |
|Steel |448 |
|Brass |386 |
|Copper |380 |
Experiments have shown that the heat transfer Q = mcΔT, where ΔT = Tfinal-Tinitial of the object you’re considering, m is its mass, and c is referred to as the “specific heat” of the material it’s made up of. For most materials over a wide range of temperatures, c is close enough to a constant value that we will consider it to be exactly constant. Note that a positive Q means that energy flowed into the object (raising its temperature), while a negative Q means that energy left the object (leaving it at a lower temperature than at the beginning). Also note that you must be careful to associate the mass, specific heat, initial temperature, and final temperature, for the appropriate object being considered in any particular calculation, and not some other object. Energy is always conserved, and this is a useful fact when dealing with heat as a kind of energy flow. If we have a
|Specific Heat for Various Materials |
|Material |Specific Heat |
| |(J/kg C°) |
|Water |4186 |
|Aluminum |900 |
|Steel |448 |
|Brass |386 |
|Copper |380 |
Experiments have shown that the heat transfer Q = mcΔT, where ΔT = Tfinal-Tinitial of the object you’re considering, m is its mass, and c is referred to as the “specific heat” of the material it’s made up of. For most materials over a wide range of temperatures, c is close enough to a constant value that we will consider it to be exactly constant. Note that a positive Q means that energy flowed into the object (raising its temperature), while a negative Q means that energy left the object (leaving it at a lower temperature than at the beginning). Also note that you must be careful to associate the mass, specific heat, initial temperature, and final temperature, for the appropriate object being considered in any particular calculation, and not some other object. Energy is always conserved, and this is a useful fact when dealing with heat as a kind of energy flow. If we have a