The second is the SI base unit of time. It underpins duration, speed and rate calculations.
The modern second is defined from an atomic transition frequency, giving it high precision and universal reproducibility.
Measurement system: International System of Units (SI). SI equivalent: Base SI time unit.
Second facts
- Unit name
- Second
- Symbol
- s
- Category
- Time
- Measurement system
- International System of Units (SI)
- SI equivalent
- Base SI time unit
- Common uses
- Experiments, motion analysis, data logging and timing
Definition of the second
The second is the SI base unit of time. It underpins duration, speed and rate calculations.
Measurement system and SI relationship
International System of Units (SI)
SI equivalent: Base SI time unit
History of the second
The modern second is defined from an atomic transition frequency, giving it high precision and universal reproducibility.
Where is the second used?
Experiments, motion analysis, data logging and timing