This new rigor does not affect how the second is used in everyday life.Ĭurrent use: As the SI base unit of time, the second and its multiples are ubiquitous. In 1967, the second was defined exactly as "9,192,631,770 times the period of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom." This definition has since been updated as of late 2018 to be more rigorously defined, but otherwise, is effectively the same. This definition was adopted as part of SI in 1960. This resulted in a second defined as "1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time," in 1956. The second was also defined as a fraction of an extrapolated year in the late 1940s with the advent of quartz crystal oscillator clocks. The second was historically defined as 1/86400 of a day in 1832, which was based on the definition of a day as the approximate amount of time required for the Earth to complete a full rotation cycle relative to the sun. History/origin: Unlike many units that have had numerous definitions throughout history, the second has only had four different definitions. It is defined based on cesium frequency, Δ νC, "by taking the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom to be 9,192,632,770 when expressed in hertz, which is equal to s -1." This definition was adopted in late 2018, and is largely the same as the previous definition, except that the conditions are more rigorously defined. This value cannot exceed 60 (0).įor more information about how to use these functions, see INT function, HOUR function, MINUTE function, and SECOND function.Definition: A second is the base unit of time in the International System of Units (SI). The difference in the seconds unit between two times. The difference in the minutes unit between two times. The difference in the hours unit between two times. To do this task, you'll use the INT function, or the HOUR, MINUTE, and SECOND functions as shown in the following example.Ĭopy the following table to a blank worksheet, and then modify as necessary. Note: If you use both a format applied with the TEXT function and apply a number format to the cell, the TEXT function takes precedence over the cell formatting.įor more information about how to use these functions, see TEXT function and Display numbers as dates or times.Įxample Table 2 - Present the result based on a single time unit Hours, minutes, and seconds between two times with the cell formatted as "h:mm:ss" by using the TEXT function (4:55:00). Hours and minutes between two times with the cell formatted as "h:mm" by using the TEXT function (4:55). Hours between two times with the cell formatted as "h" by using the TEXT function (4). You must manually apply the custom format "h:mm:ss" to the cell. Hours, minutes, and seconds between two times (4:55:00). You must manually apply the custom format "h:mm" to the cell. Hours and minutes between two times (4:55). You must manually apply the custom format "h" to the cell. Example Table 1 - Present the result in the standard time formatĬopy the following table to a blank worksheet, and then modify if necessary. Use the TEXT function to format the times: When you use the time format codes, hours never exceed 24, minutes never exceed 60, and seconds never exceed 60. In the Format Cells dialog box, click Custom in the Category list, and then select a custom format in the Type box. On the Home tab, in the Number group, click the arrow next to the General box, and then click More Number Formats. You use the subtraction operator ( -) to find the difference between times, and then do either of the following:Īpply a custom format code to the cell by doing the following: There are two approaches that you can take to present the results in the standard time format (hours : minutes : seconds). Present the result in the standard time format There are several ways to calculate the difference between two times. Let's say that you want find out how long it takes for an employee to complete an assembly line operation or a fast food order to be processed at peak hours.
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