what is the second law of thermodynamics physics
Second law of thermodynamics The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time. The total entropy can remain constant in ideal cases where the system is in a steady state (equilibrium), or is undergoing a reversible process. In all spontaneous processes,[1] the total entropy always increases and the process is irreversible. The increase in entropy accounts for the irreversibility of natural processes, and the asymmetry between future and past.[2]
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.