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The TU (for time unit) is a unit of time defined as 1024 μs for use in engineering. The Svedberg is a time unit used for sedimentation rates (usually of proteins). It is defined as 10 −13 seconds (100 fs). The galactic year, based on the rotation of the galaxy and usually measured in million years.
The United States Naval Observatory states "the Equation of Time is the difference apparent solar time minus mean solar time ", i.e. if the sun is ahead of the clock the sign is positive, and if the clock is ahead of the sun the sign is negative. [6] [7] The equation of time is shown in the upper graph above for a period of slightly more than a ...
Sidereal time is a "time scale that is based on Earth's rate of rotation measured relative to the fixed stars ". [1] Viewed from the same location, a star seen at one position in the sky will be seen at the same position on another night at the same time of day (or night), if the day is defined as a sidereal day (also known as the sidereal ...
The division of a year for each is twelve 30-day months or 360 days, where a day is divided into a 12-hour day proper and 12-hour night. [20] A 30-day month amounts to four 7-day weeks with an extra 8th day every two weeks (48-week year).
A semester (one-half of a full year) earns 1/2 a Carnegie Unit. [1] The Student Hour is approximately 12 hours of class or contact time, approximately 1/10 of the Carnegie Unit (as explained below). As it is used today, a Student Hour is the equivalent of one hour (50 minutes) of lecture time for a single student per week over the course of a ...
It includes time for breaks and can be used to calculate how long it may take to complete a task, including required recovery times from physically strenuous work, as well as legally required breaks or other human interactions. If it includes 15-minute breaks, it is written as (PSH15). A related concept is productive machine hours (PMH).
A plot of hours of daylight as a function of the date for changing latitudes. This plot was created using the simple sunrise equation, approximating the sun as a single point and does not take into account effects caused by the atmosphere or the diameter of the Sun. The sunrise equation or sunset equation can be used to derive the time of ...
Midnight to 1 a.m. on a 24-hour clock with a digital face. An hour ( symbol: h; [1] also abbreviated hr) is a unit of time historically reckoned as 1⁄24 of a day and defined contemporarily as exactly 3,600 seconds ( SI ). There are 60 minutes in an hour, and 24 hours in a day.