Chemical reactions, engines, and collisions have force, energy, and heat transfers {thermodynamics}|.
heat
Energy transfers use work, through directed kinetic energy, or heat, through temperature change or state change. Friction changes some directed energy into random energy and increases temperature. Systems can minimize friction by slowing and by using lubricants.
comparison
Thermodynamics is about extensive quantities. Statistical mechanics is about intensive quantities. Thermodynamic quantities are number of moles times Avogadro's number times corresponding statistical-mechanics quantity. Molecular-property time averages give observable thermodynamic properties.
potentials
The six thermodynamic potentials are baryon-number density, total mass-energy density, isotropic pressure, temperature, entropy per baryon, and baryon chemical potential. Rest frame is stationary or moving fluid. Baryon number density and entropy per baryon determine composition. Baryon number is constant in fluid, because density is constant, so gradient equals zero. Systems can only create entropy, not destroy it. Shock waves increase entropy. Heat flows increase or decrease entropy.
Material transport {heat transport} properties, such as electric conductivity, thermal conductivity, viscosity, diffusion, effusion, and dissolution, depend on molecular properties such as temperature, pressure, collision frequency, and kinetic-energy range.
Heat flows have laws {thermodynamics laws}. When heat becomes another energy type or another energy type becomes heat, total energy does not change {energy conservation, first law} {first law of thermodynamics}. Heat flows from objects with higher temperature to objects with lower temperature, and energy must make heat flow from cold object to hot object {second law of thermodynamics}. Entropy is zero at absolute zero temperature {third law of thermodynamics}, because random motion is zero and system has complete order. Two systems in thermal equilibrium with third system have same temperature {zeroth law of thermodynamics}.
Systems react to change, such as energy change, to oppose further change {Le Chatelier's principle} {Le Chatelier principle}. As system resists change, directed work energy becomes random translational kinetic energy, through temperature and pressure change.
Systems with energy flows can have steady or periodic flow {steady state, thermodynamics}, rather than reach equilibrium. Movement rate or flux depends on gradient or force, so flow rate equals force or gradient sum. Steady states are irreversible thermodynamically. Entropy minimizes, because systems with forces or gradients can reduce entropy.
Perhaps, motion never slows {perpetual motion}|. Perpetual motion of first kind violates extended Le Chatelier's principle. Perpetual motion of second kind violates extended Le Chatelier's principle. Perpetual motion of third kind violates the principle that there must always be friction.
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225