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Power is the rate with respect to time at which work is done; it is the time derivative of work: =, where P is power, W is work, and t is time.. We will now show that the mechanical power generated by a force F on a body moving at the velocity v can be expressed as the product: = =
In science, work is the energy transferred to or from an object via the application of force along a displacement.In its simplest form, for a constant force aligned with the direction of motion, the work equals the product of the force strength and the distance traveled.
Useful output energy is always lower than input energy. Efficiency of power plants, world total, 2008. Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical, electric power, mechanical work, light (radiation ...
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.
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.
Therefore, the efficiency of all real machines is less than 1. A hypothetical machine without friction is called an ideal machine; such a machine would not have any energy losses, so its output power would equal its input power, and its efficiency would be 1 (100%). For hydropower turbines the efficiency is referred to as hydraulic efficiency ...
The energy input might be rendered in several different types depending on the type of propulsion, and normally such energy is presented in liquid fuels, electrical energy or food energy. [ 1 ] [ 2 ] The energy efficiency is also occasionally known as energy intensity . [ 3 ]
Mass–energy equivalence states that all objects having mass, or massive objects, have a corresponding intrinsic energy, even when they are stationary.In the rest frame of an object, where by definition it is motionless and so has no momentum, the mass and energy are equal or they differ only by a constant factor, the speed of light squared (c 2).