Browse Definitions:
Definition

energy

Energy is the capacity of a physical system to do work. The common symbol for energy is the uppercase letter E. The standard unit is the joule, symbolized by J. One joule (1 J) is the energy resulting from the equivalent of one newton (1 N) of force acting over one meter (1 m) of displacement. There are two main forms of energy, called potential energy and kinetic energy.

Potential energy, sometimes symbolized U, is energy stored in a system. A stationary object in a gravitational field, or a stationary charged particle in an electric field, has potential energy.

Kinetic energy is observable as motion of an object, particle, or set of particles. Examples include the falling of an object in a gravitational field, the motion of a charged particle in an electric field, and the rapid motion of atoms or molecules when an object is at a temperature above zero Kelvin.

Matter is equivalent to energy in the sense that the two are related by the Einstein equation:

E = mc2

where E is the energy in joules, m is the mass in kilograms, and c is the speed of light, equal to approximately 2.99792 x 108 meters per second.

In electrical circuits, energy is a measure of power expended over time. In this sense, one joule (1 J) is equivalent to one watt (1 W) dissipated or radiated for one second (1 s). A common unit of energy in electric utilities is the kilowatt-hour (kWh), which is the equivalent of one kilowatt (kW) dissipated or expended for one hour (1 h). Because 1 kW = 1000 W and 1 h = 3600 s, 1 kWh = 3.6 x 106 J.

Heat energy is occasionally specified in British thermal units (Btu) by nonscientists, where 1 Btu is approximately equal to 1055 J. The heating or cooling capability of a climate-control system may be quoted in Btu, but this is technically a misuse of the term. In this sense, the system manufacturer or vendor is actually referring to Btu per hour (Btu/h), a measure of heating or cooling power.

This was last updated in September 2005

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

  • audit program (audit plan)

    An audit program, also called an audit plan, is an action plan that documents what procedures an auditor will follow to validate ...

SearchSecurity

  • insider threat

    Insider threat is a generic term for a threat to an organization's security or data that comes from within.

  • ransomware

    Ransomware is a subset of malware in which the data on a victim's computer is locked, typically by encryption, and payment is ...

  • hacker

    A hacker is an individual who uses computer, networking or other skills to overcome a technical problem.

SearchHealthIT

SearchDisasterRecovery

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

SearchStorage

SearchSolidStateStorage

  • 3D XPoint

    3D XPoint is memory storage technology jointly developed by Intel and Micron Technology Inc.

  • RRAM or ReRAM (resistive RAM)

    RRAM or ReRAM (resistive random access memory) is a form of nonvolatile storage that operates by changing the resistance of a ...

  • JEDEC

    JEDEC is a global industry group that develops open standards for microelectronics.

SearchCloudStorage

  • Google Cloud Storage

    Google Cloud Storage is an enterprise public cloud storage platform that can house large unstructured data sets.

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

Close