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A picosecond (abbreviated as ps) is a unit of time in the International System of Units (SI) equal to 10 −12 or 1 ⁄ 1 000 000 000 000 (one trillionth) of a second. That is one trillionth, or one millionth of one millionth of a second, or 0.000 000 000 001 seconds. A picosecond is to one second, as one second is to approximately 31,688.76 years.
In statistics, the 68–95–99.7 rule, also known as the empirical rule, and sometimes abbreviated 3sr or 3 σ, is a shorthand used to remember the percentage of values that lie within an interval estimate in a normal distribution: approximately 68%, 95%, and 99.7% of the values lie within one, two, and three standard deviations of the mean ...
For example, the year cannot be divided into twelve 28-day months since 12 times 28 is 336, well short of 365. The lunar month (as defined by the moon's rotation) is not 28 days but 28.3 days. The year, defined in the Gregorian calendar as 365.2425 days has to be adjusted with leap days and leap seconds. Consequently, these units are now all ...
(1 hs = 1 min 40 s = 100 s) 2 hs (3 min 20 s): The average length of the most popular YouTube videos as of January 2017 [15] 5.55 hs (9 min 12 s): The longest videos in the above study 7.1 hs (11 m 50 s): The time for a human walking at average speed of 1.4 m/s to walk 1 kilometre 10 3: kilosecond ks minutes, hours, days (1 ks = 16 min 40 s ...
A femtosecond is equal to 1000 attoseconds, or 1/1000 picosecond. Because the next higher SI unit is 1000 times larger, times of 10 −14 and 10 −13 seconds are typically expressed as tens or hundreds of femtoseconds. Typical time steps for molecular dynamics simulations are on the order of 1 fs. [4]
The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer (American spelling) is a unit of length in the International System of Units (SI), equal to 1 × 10 −12 m, or one trillionth ( 1 / 1 000 000 000 000 ) of a metre, which is the SI base unit of length.
1 cm – 0.39 inches; 1 cm – edge of a square of area 1 cm 2; 1 cm – edge of a cube of volume 1 mL; 1 cm – length of a coffee bean; 1 cm – approximate width of average fingernail; 1.2 cm – length of a bee; 1.2 cm – diameter of a die; 1.5 cm – length of a very large mosquito; 1.6 cm – length of a Jaragua Sphaero, a very small reptile
Of more interest is the frequency separation between any two adjacent modes q and q + 1; this is given (for an empty linear resonator of length L) by Δν = c / 2L, where c is the speed of light (≈ 3×10 8 m/s). Using the above equation, a small laser with a mirror separation of 30 cm has a frequency separation between longitudinal modes of 0 ...