In engineering, the terms specific power or power density can refer to power either per unit of mass, volume or area. Engineering is the Discipline and Profession of applying technical and scientific Knowledge and In Physics, power (symbol P) is the rate at which work is performed or energy is transmitted or the amount of energy required or expended for Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically Area is a Quantity expressing the two- Dimensional size of a defined part of a Surface, typically a region bounded by a closed Curve. The following sections give several examples of where these terms are used.

## Power per unit of volume

• Heat engines can be characterized by their specific power, which is typically given in kilowatts per litre of engine displacement (in the U. A heat engine is a physical or theoretical device that converts Thermal energy to mechanical output The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. The litre or liter (see spelling differences) is a unit of Volume. Engine displacement is defined as the total Volume of air/fuel mixture an Engine can draw in during one complete engine cycle it is normally stated in Cubic S. also horsepower per cubic inch). A cubic inch (plural cubic inches) is a non- SI unit of Volume, equal to the volume of a Cube with sides of one Inch. The result offers an approximation of the peak-power output of an engine. This is not to be confused with fuel efficiency, since high-efficiency often requires a lean fuel-air ratio, and thus lower power density. Fuel efficiency, in its basic sense is the same as Thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier A modern high-performance car engine makes in excess of 75 kW/L (1. 65 hp/in³).

## Power per unit of mass

• With batteries, specific power usually refers to the power-to-weight ratio, measured in kilowatts per kilogram (generally, W/kg). In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy Power-to-weight ratio (specific power is a calculation commonly applied to Engines and other mobile power sources to enable the comparison of one unit or design to another W is the twenty-third letter in the Latin alphabet. Its name in English is spelled double-u (ˈdʌbljuː Fuels are usually measured in terms of energy density, since the available power is usually not a limitation. Energy density is the amount of Energy stored in a given system or region of space per unit Volume, or per unit Mass, depending on the context although A high-octane fuel actually burns more slowly, and due to engine dynamics this can actually allow an engine to produce more power. The octane rating is a measure of the resistance of Gasoline and other Fuels to Detonation ( Engine knocking) in spark-ignition In high performance vehicles, the specific power determines the vehicle's acceleration.
• The specific power on a mass basis is also used to characterize solar panels for use in aerospace applications where this parameter is critical for an efficient launch. This article is about the field of research and industry for the corporation see The Aerospace Corporation Aerospace comprises the

## Power per unit of area

• The intensity of electromagnetic waves can be expressed in W/m². Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. An example of such a quantity is the solar constant.
• Wind turbines are often compared using a specific power measuring watts per square meter of turbine disk area, which is pi times the length of a blade squared. A wind turbine is a rotating machine which converts the Kinetic energy in Wind into Mechanical energy. M^2 redirects here For other uses see M². CM2 redirects here IMPORTANT NOTICE Please note that Wikipedia is not a database to store the millions of digits of π please refrain from adding those to Wikipedia as it could cause technical problems This measure is also commonly used for solar panels, at least for typical applications. In the field of Photovoltaics, a photovoltaic module is a packaged interconnected assembly of photovoltaic cells also known as Solar cells An installation of