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)

SearchNetworking
  • virtual network functions (VNFs)

    Virtual network functions (VNFs) are virtualized tasks formerly carried out by proprietary, dedicated hardware.

  • network functions virtualization (NFV)

    Network functions virtualization (NFV) is a network architecture model designed to virtualize network services that have ...

  • overlay network

    An overlay network is a virtual or logical network that is created on top of an existing physical network.

SearchSecurity
  • X.509 certificate

    An X.509 certificate is a digital certificate that uses the widely accepted international X.509 public key infrastructure (PKI) ...

  • directory traversal

    Directory traversal is a type of HTTP exploit in which a hacker uses the software on a web server to access data in a directory ...

  • malware

    Malware, or malicious software, is any program or file that is intentionally harmful to a computer, network or server.

SearchCIO
  • data latency

    Data latency is the time it takes for data packets to be stored or retrieved. In business intelligence (BI), data latency is how ...

  • chief data officer (CDO)

    A chief data officer (CDO) in many organizations is a C-level executive whose position has evolved into a range of strategic data...

  • information technology (IT) director

    An information technology (IT) director is the person in charge of technology within an organization. IT directors manage ...

SearchHRSoftware
SearchCustomerExperience
  • implementation

    Implementation is the execution or practice of a plan, a method or any design, idea, model, specification, standard or policy for...

  • first call resolution (FCR)

    First call resolution (FCR) is when customer service agents properly address a customer's needs the first time they call.

  • customer intelligence (CI)

    Customer intelligence (CI) is the process of collecting and analyzing detailed customer data from internal and external sources ...

Close