Work
the work is an ordered transfer of energy between a system and the external medium.
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Let us consider a unit Cylindre, Piston, which is at the base of mechanical obtaining work per action of heat. On the scale Microscopique the Choc S of the Particule S of Gaz on the piston define the Pression exerted on this one on the scale Macroscopique. Each shock contributes to the displacement, concerted with the other shocks, of the piston in the same direction. There is addition of the forces induced by each shock and this is why the transfer of energy is regarded as ordered.
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If electric work now is considered. It is due to the displacement of the electron S in a Conducteur under the influence of a Electric field. Here still the whole of the electrons moves in the same direction and the effects are added at the macroscopic level.
Heat
the Chaleur is a disordered transfer of energy between the system and the external medium .- heat is a thermal transfer of agitation. The agitation of the particles is propagated with the liking of the shocks in all the directions, in a disordered way. For this reason one can never completely transform calorific energy into work whereas the reverse is possible (ex: electric work transformed into heat by Joule effect in an electric radiator). One still says that heat is a degraded form of energy. is
- Comment transmitted heat? The hottest system, i.e. that of which the particles statistically are agitated, will transmit its thermal agitation to the liking of the more or less energy shocks, the external medium or the system statistically less agitated, i.e. coldest. This intuitive observation is formalized by the Second principle of thermodynamics.
Conclusion
Work and heat are not functions of state. Their quantity, setting concerned during a transformation, depends on the way in which one proceeds.
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