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. One second is equal to 1/86,400 of a mean solar day.
Is 1 second long?
Since 1967, the second has been defined as exactly the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom (at a temperature of 0 K).
Why is it called a second time?
Historical origin. Originally, the second was known as a second minute, meaning the second minute (i.e. small) division of an hour. The first division was known as a prime minute and is equivalent to the minute we know today. Third and fourth minutes were sometimes used in calculations.
How fast is second?
The answer, simply, is that a second is 1/60th of a minute, or 1/3600th of an hour.
What is it called when a second?
TIL a second is called a second because it is the second division of the hour by 60, the first being a minute.: todayilearned.
Who decided how long a second is?
The Persian scholar Al-Biruni first used the term second around 1000. He defined it—as well as the day, hour, and minute—as fractions according to the lunar cycle.
How 1 second is measured?
Definition. The second is defined by taking the fixed numerical value of the caesium frequency ∆ν, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s−1. The wording of the definition was updated in 2019.
What does 2nd mean?
adjective. next after the first; being the ordinal number for two. being the latter of two equal parts. next after the first in place, time, or value: the second house from the corner. next after the first in rank, grade, degree, status, or importance: the second person in the company.
Who defined how long a second is?
In 1967, the Thirteenth General Conference of the International Committee for Weights and Measures officially defined the second as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. And that has remained ...