what do the various forms of energy have in common
Energy In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.[note 1] Energy is a conserved quantity; the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton.
Heat In thermodynamics, heat is energy transferred from one system to another as a result of thermal interactions.[1] The amount of heat transferred in any process can be defined as the total amount of transferred energy excluding any macroscopic work that was done and any transfer of part of the object itself.[2][3][4][5][6] When two systems with different temperatures are put in contact, heat flows spontaneously from the hotter to the colder system. Transfer of energy as heat can occur through direct contact, through a barrier that is impermeable to matter (as in conduction), by radiation between separated bodies, by way of an intermediate fluid (as in convective circulation), or by a combination of these.[7][8][9] By contrast to work, heat involves the stochastic (random) motion of particles (such as atoms or molecules) that is equally distributed among all degrees of freedom, while work is confined to one or more specific degrees of freedom such as those of the center of mass.