Browse Definitions:
Definition

second (s or sec)

The second (abbreviation, s or sec) is the Standard International ( SI ) unit of time. One second is the time that elapses during 9,192,631,770 (9.192631770 x 10 9 ) cycles of the radiation produced by the transition between two levels of the cesium 133 atom.

There are other expressions for the second. It is the time required for an electromagnetic field to propagate 299,792,458 meters (2.99792458 x 10 8 m) through a vacuum. This figure is sometimes rounded to 3.00 x 10 8 m, or 300,000 kilometers (3.00 x 10 5 km). One second is equal to 1/86,400 of a mean solar day. This is easy to derive from the fact that there are 60 seconds in a minute, 60 minutes in an hour, and 24 hours in a mean solar day. This definition is, however, subject to limited accuracy because of irregularities in the earth's orbit around the sun.

Engineers and scientists often use smaller units than the second by attaching power-of-10 prefix multiplier s. One millisecond is 10 -3 s; one microsecond is 10 -6 s; one nanosecond is 10 -9 s; one picosecond is 10 -12 s. During these spans of time, respectively, an EM field propagates through a vacuum over distances of approximately 300 kilometers, 300 meters, 300 millimeters, and 300 micrometers.

The second is sometimes specified as a unit of angular measure, especially in astronomy and global positioning. In these contexts, it is also known as an arc second or a second of arc, and is equal to exactly 1/3600 of an angular degree or 1/1,296,000 of a circle. Sixty arc seconds comprise an arc minute; 60 arc minutes comprise an angular degree. One arc second of latitude at the earth's surface corresponds to a north-south distance of only about 31 m.

Also see Standard International ( SI ) System of Units and prefix multiplier s.

This was last updated in March 2011

Continue Reading About second (s or sec)

Join the conversation

1 comment

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.

"s" is the SI unit for time (seconds)
"sec" is secant, the reciprocal of cosine
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

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

  • computer worm

    A computer worm is a type of malicious software program whose primary function is to infect other computers while remaining ...

  • black hat

    Black hat refers to a hacker who breaks into a computer system or network with malicious intent.

  • copyright

    Copyright is a legal term describing ownership of control of the rights to the use and distribution of certain works of creative ...

SearchHealthIT

SearchDisasterRecovery

  • 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 ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

SearchStorage

  • non-volatile memory (NVM)

    Non-volatile memory (NVMe) is a semiconductor technology that does not require a continuous power supply to retain the data or ...

  • hybrid hard drive (HHD)

    A hybrid hard drive (HHD), sometimes known as a solid-state hybrid drive (SSHD), is a mass storage device that combines a ...

  • USB flash drive

    A USB flash drive -- also known as a stick, thumb or pen drive -- is a plug-and-play portable storage device that uses flash ...

SearchSolidStateStorage

  • 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.

  • M.2 SSD

    An M.2 SSD is a solid-state drive (SSD) that conforms to a computer industry specification written for internally mounted storage...

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