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In physics, the Poynting vector (or Umov–Poynting vector) represents the directional energy flux (the energy transfer per unit area, per unit time) or power flow of an electromagnetic field. The SI unit of the Poynting vector is the watt per square metre (W/m 2 ); kg/s 3 in base SI units.
In physics, action is a scalar quantity that describes how the balance of kinetic versus potential energy of a physical system changes with trajectory. Action is significant because it is an input to the principle of stationary action, an approach to classical mechanics that is simpler for multiple objects. [1]
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 (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light.
The ancient Greek understanding of physics was limited to the statics of simple machines (the balance of forces), and did not include dynamics or the concept of work. During the Renaissance the dynamics of the Mechanical Powers, as the simple machines were called, began to be studied from the standpoint of how far they could lift a load, in addition to the force they could apply, leading ...
where is the energy input to the system, which has mass , that is used to move the system a distance , and is Standard gravity. Alternatively, one can use the power input to the system used to move the system at a constant velocity . The cost of transport is non-dimensional.
Integrals and derivatives of displacement, including absement, as well as integrals and derivatives of energy, including actergy. (Janzen et al. 2014) In kinematics, absement (or absition) is a measure of sustained displacement of an object from its initial position, i.e. a measure of how far away and for how long.
Perpendicular distance between repeating units of a wave m L: Wavenumber: k: Repetency or spatial frequency: the number of cycles per unit distance m −1: L −1: scalar Work: W: Transferred energy joule (J) L 2 M T −2: scalar Young's modulus: E: Ratio of stress to strain pascal (Pa = N/m 2) L −1 M T −2: scalar; assumes isotropic linear ...