Browse Definitions :
Definition

second (s or sec)

What is a second (s or sec)?

The second (s or sec) is the International System of Units (SI) unit of time measurement.

One second is the time that elapses during 9,192,631,770 (or 9.192631770 x 109 in decimal form) cycles of the radiation produced by the transition between two levels of the cesium-133 atom.

How is a second expressed?

There are other expressions for the second. It is the time required for an electromagnetic (EM) field to propagate 299,792,458 meters (2.99792458 x 108 m) through a vacuum.

This figure is sometimes rounded to 3 x 108 m, or 300,000 kilometers (3 x 105 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.

A second is the international standard unit of time
A second is typically the base unit of time measurement for everyday events.

Are their units of time smaller than seconds?

Engineers and scientists often use smaller units of measurement than the second by attaching power-of-10 prefix multipliers. One millisecond is 10-3 seconds; 1 microsecond is 10-6 seconds; 1 nanosecond is 10-9 seconds; and 1 picosecond is 10-12 seconds.

During these spans of time, respectively, an EM field propagates through a vacuum over distances of approximately 300 km, 300 m, 300 millimeters and 300 micrometers.

Use cases for seconds

A second is typically the base unit of time measurement in timing for events that occur in everyday life, such as the following:

  • a person's heart rate (beats per minute);
  • a car's speed (miles per hour or kilometers per hour); and
  • cooking time frames (minutes and seconds).

The smaller subdivisions are usually used for events that occur rapidly, such as the following:

The second is also a common base unit for expressing extremely long spans of time, such as geologic time units, like the millennium, mega-annum, or giga-annum.

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 1/3,600 of an angular degree or 1/1,296,000 of a circle.

Sixty arc seconds constitute an arc minute; 60 arc minutes constitute an angular degree. One arcsecond of latitude at the earth's surface corresponds to a north-south distance of only about 31 m.

At the equator, 1 second of longitude corresponds to an east-west distance of about 26 m.

See also: table of physical constants, atomic clock, radiant energy, pascal and newton.

This was last updated in June 2022

Continue Reading About second (s or sec)

Networking
  • firewall as a service (FWaaS)

    Firewall as a service (FWaaS), also known as a cloud firewall, is a service that provides cloud-based network traffic analysis ...

  • private 5G

    Private 5G is a wireless network technology that delivers 5G cellular connectivity for private network use cases.

  • NFVi (network functions virtualization infrastructure)

    NFVi (network functions virtualization infrastructure) encompasses all of the networking hardware and software needed to support ...

Security
  • virus (computer virus)

    A computer virus is a type of malware that attaches itself to a program or file. A virus can replicate and spread across an ...

  • Certified Information Security Manager (CISM)

    Certified Information Security Manager (CISM) is an advanced certification that indicates that an individual possesses the ...

  • cryptography

    Cryptography is a method of protecting information and communications using codes, so that only those for whom the information is...

CIO
  • B2B (business to business)

    B2B (business-to-business) is a type of commerce involving the exchange of products, services or information between businesses, ...

  • return on investment (ROI)

    Return on investment (ROI) is a crucial financial metric investors and businesses use to evaluate an investment's efficiency or ...

  • big data as a service (BDaaS)

    Big data as a service (BDaS) is the delivery of data platforms and tools by a cloud provider to help organizations process, ...

HRSoftware
  • talent acquisition

    Talent acquisition is the strategic process an organization uses to identify, recruit and hire the people it needs to achieve its...

  • human capital management (HCM)

    Human capital management (HCM) is a comprehensive set of practices and tools used for recruiting, managing and developing ...

  • Betterworks

    Betterworks is performance management software that helps workforces and organizations to improve manager effectiveness and ...

Customer Experience
  • martech (marketing technology)

    Martech (marketing technology) refers to the integration of software tools, platforms, and applications designed to streamline ...

  • transactional marketing

    Transactional marketing is a business strategy that focuses on single, point-of-sale transactions.

  • customer profiling

    Customer profiling is the detailed and systematic process of constructing a clear portrait of a company's ideal customer by ...

Close