second

Also known as s, seconds, sec., sec

The second (symbol: s) is a unit of time derived from the division of the day, first into hours, then into minutes, and lastly into seconds, for a total of 24 × 60 × 60 = seconds per day. That definition, based on of a rotation of the Earth, is still used by the Universal Time 1 (UT1) system.

AI overview

A second is a unit of time that results from dividing a day into progressively smaller units—first into 24 hours, then into 60 minutes, and finally into 60 seconds each, giving 86,400 seconds per day. This measurement system, originally based on Earth's rotation, remains the foundation of the Universal Time 1 (UT1) timekeeping system used today.

AI-generated from the Wikipedia summary — may contain errors.

Key facts

Unit.name: second
Unit.image: File:Clock-pendulum.gif
Unit.caption: A pendulum-governed escapement of a clock, ticking every second
Unit.standard: SI
Unit.quantity: time
Unit.symbol: s

via Wikipedia infobox

Wikidata facts

Show 10 more facts

exact match: www.w3.org/TR/owl-time/#time:unitSecond
short name: sek.
conversion to standard unit: 9192631770
Commons category: Second
conversion to SI unit: 1
Commons gallery: Second
Wikidata time precision: 14
numeric value: 0.000000031688764640818492441649983866417932843660808436937693280217
Wikidata SPARQL query equivalent: wd:Q11574 p:P2370/psn:P2370 [wikibase:quantityAmount ?source; wikibase:quantityUnit ?base]. ?item p:P2370/psn:P2370 [wikibase:quantityAmount ?target; wikibase:quantityUnit ?base]. BIND(?source / ?target as ?value)
unit symbol: s

Sources (7)

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~23 min read

Article

21 sections

Contents

Etymology
Uses
Clocks and solar time
Events and units of time in seconds
Other units incorporating seconds
Timekeeping standards
Optical lattice clock
History of definition
Sexagesimal divisions of calendar time and day
Fraction of solar day
Fraction of an ephemeris year
Atomic definition
Table
Future redefinition
Rydberg constant
Requirements
SI multiples
See also
Notes
References
External links

The current and formal definition in the International System of Units (SI) is more precise:The second [...] is defined by taking the fixed numerical value of the caesium (Cs) frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the Cs-133 atom, to be when expressed in the unit hertz, which is equal to s−1.