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where: is the rate of change of the energy density in the volume. ∇•S is the energy flow out of the volume, given by the divergence of the Poynting vector S. J•E is the rate at which the fields do work on charges in the volume (J is the current density corresponding to the motion of charge, E is the electric field, and • is the dot product).
Energy flow is the flow of energy through living things within an ecosystem. [1] All living organisms can be organized into producers and consumers , and those producers and consumers can further be organized into a food chain .
"Energy current" is a somewhat informal term that is used, on occasion, to describe the process of energy transfer in situations where the transfer can usefully be viewed in terms of a flow. It is particularly used when the transfer of energy is more significant to the discussion than the process by which the energy is transferred.
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).
The flow of heat from Earth's interior to the surface is estimated at 47±2 terawatts (TW) [1] and comes from two main sources in roughly equal amounts: the radiogenic heat produced by the radioactive decay of isotopes in the mantle and crust, and the primordial heat left over from the formation of Earth. [2]
When a system transforms reversibly from an initial state to a final state under these conditions, the decrease in Gibbs free energy equals the work done by the system to its surroundings, minus the work of the pressure forces. [1] The Gibbs energy is the thermodynamic potential that is minimized when a system reaches chemical equilibrium at ...
Energy – in physics, this is an indirectly observed quantity often understood as the ability of a physical system to do work on other physical systems. [1] [2] Since work is defined as a force acting through a distance (a length of space), energy is always equivalent to the ability to exert force (a pull or a push) against an object that is ...
The energy dispersal approach avoids the ambiguous term 'disorder'. An early advocate of the energy dispersal conception was Edward A. Guggenheim in 1949, using the word 'spread'. [1] [2] In this alternative approach, entropy is a measure of energy dispersal or spread at a specific temperature.