What kind of energy travels from warm bodies to cooler bodies?
Answers (2)
Heat is a form of energy. As discussed earlier, while we rub our hands, the energy spent in overcoming friction is converted into heat energy, or simply the mechanical energy is converted to heat. Matter contains heat in the form of kinetic energy and potential energy. The total mechanical energy, i.e. potential energy + kinetic energy, is hence called thermal energy.
The thermal energy in a particular body is proportional to the amount of inter-molecular vibration. This means that as the vibration increases the thermal energy also increases. So, hot bodies have more thermal energy than cold bodies. We know that when a hot body and a cold body are kept in contact with each other, the vibrations travel from the hot body to the cold.
Let's now define heat considering all the conditions:
Heat is a type of mechanical energy, which is stored in matter in the form of vibrational energy. It is the amount of thermal energy that flows from a hot body to a cold body.
SI unit: Joule
Energy is not a physical unit. It is a philosophical concept and an accounting technique used to analyze mechanical and chemical exchanges. In nuclear physics it is defined as a wavelength of light, in biology it is a synonym for metabolism, and in public utilities they say energy when they mean connectivity. Anybody who uses the word in any other context either does not know what he is talking about, or is peddling something you don't need.
Some people say energy is the capacity to do work. Work is disordering of energy. So energy is capacity to do disordering of energy. That is a circular definition.