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The second law of thermodynamics is a physical law based on universal empirical observation concerning heat and energy interconversions.A simple statement of the law is that heat always flows spontaneously from hotter to colder regions of matter (or 'downhill' in terms of the temperature gradient).
Traditionally, thermodynamics has recognized three fundamental laws, simply named by an ordinal identification, the first law, the second law, and the third law. [1] [2] [3] A more fundamental statement was later labelled as the zeroth law after the first three laws had been established.
The law was actually the last of the laws to be formulated. First law of thermodynamics. d U = δ Q − δ W {\displaystyle dU=\delta Q-\delta W} where. d U {\displaystyle dU} is the infinitesimal increase in internal energy of the system, δ Q {\displaystyle \delta Q} is the infinitesimal heat flow into the system, and.
The zeroth law was not initially recognized as a separate law of thermodynamics, as its basis in thermodynamical equilibrium was implied in the other laws. The first, second, and third laws had been explicitly stated already, and found common acceptance in the physics community before the importance of the zeroth law for the definition of ...
The first law of thermodynamics states that: where and are infinitesimal amounts of heat supplied to the system by its surroundings and work done by the system on its surroundings, respectively. According to the second law of thermodynamics we have for a reversible process: Q {\displaystyle \mathrm {d} S= {\frac {\delta Q} {T}}\,} Hence:
The Clausius theorem is a mathematical representation of the second law of thermodynamics. It was developed by Rudolf Clausius who intended to explain the relationship between the heat flow in a system and the entropy of the system and its surroundings.
Entropy is one of the few quantities in the physical sciences that require a particular direction for time, sometimes called an arrow of time. As one goes "forward" in time, the second law of thermodynamics says, the entropy of an isolated system can increase, but not decrease. Thus, entropy measurement is a way of distinguishing the past from ...
Clausius restated the two laws of thermodynamics to overcome this contradiction. This paper made him famous among scientists. (The third law was developed by Walther Nernst, during the years 1906–1912). Clausius's most famous statement of the second law of thermodynamics was published in German in 1854, [10] and in English in 1856. [11]