What unit of measurement is hr?

Hour measurement unit. The English expression for hour is hour, and the abbreviation is hr. When doing math or physics problems, most of the abbreviations for the unit are h, which are abbreviations for the unit of hours. They only have different expressions, but the meaning is the same and there is no difference.

The origin of the time unit "hour": Ancient China used the "copper kettle drip" method to measure time, dividing day and night into twelve hours. One hour is equivalent to two o'clock on a Western clock.

When clocks were introduced to China from the West, people called one hour in China "big time" and one hour in the West called "hour". Later, with the popularity of clocks and watches, the term "big time" gradually disappeared, while "hour" has been used to this day.

Before the founding of the Republic of China, the twelve earthly branches were used to keep time. The earthly branches represented not only the year, month, and day, but also the hour. The day was divided into Zi, Chou, Yin, Mao, Chen, Si, Wu, and Wei. , Shen, You, Xu, Hai twelve hours.

After the founding of the Republic of China, the AD was used to record the year, month, day, and hour, while retaining the Chinese lunar calendar. The AD time was divided into 24 hours, one day smaller than the traditional twelve hours. times, so it is called an hour.