What is the relationship between heat and water?

Answer 1

The process of changing one form of energy into another form of energy is called work (symbol: W). For example, when an electric motor changes electric energy into kinetic energy, it is doing work.

Heat (symbol: Q) describes energy in transit (i.e. the flow of energy) from a warmer body to a cooler body.

So, for example, when an electric kettle is switched on, electrical energy is converted into the internal energy of the water (and of the kettle itself) -in other words, work(W) is being done to the kettle. As the internal energy* of the water and the kettle increases, its temperature rises above the abient (surrounding) temperature, so energy is then lost from the kettle to its surroundings by heat(Q) transfer. So, the change in the water/kettle's internal energy is the difference between the work done on the kettle, and the heat transfer away from the kettle. To summarise:

change in internal energy = W - Q

So, we can say that a change in internal energy is the difference between work and heat. And this is the relationship between work and heat.

(*'Internal energy' is the sum total of the various energies associated with the vibration of the molecules of any body. All bodies have internal energy. Lower internal energy is associated with lower temperatures, and higher internal energy is associated with higher temperatures.)

Answer 2

The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. The relationship between heat and temperature change is usually expressed in the form shown below where c is the specific heat. The relationship does not apply if a phase change is encountered, because the heat added or removed during a phase change does not change the temperature.