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A microsecond is to one second, as one second is to approximately 11.57 days. A microsecond is equal to 1000 nanoseconds or 1 ⁄ 1,000 of a millisecond. Because the next SI prefix is 1000 times larger, measurements of 10 −5 and 10 −4 seconds are typically expressed as tens or hundreds of microseconds.
One barn is equal to 1.0 × 10 −28 m 2. The name derives from the folk expressions "As big as a barn," and "Couldn't hit the broad side of a barn", used by particle accelerator physicists to refer to the probability of achieving a collision between particles. For nuclear purposes, 1.0 × 10 −28 m 2 is actually rather large. [25]
One hundredth of one second 1.6667 cs: The period of a frame at a frame rate of 60 Hz. 2 cs: The cycle time for European 50 Hz AC electricity 10–20 cs (=0.1–0.2 s): The human reflex response to visual stimuli 10 −1: decisecond ds One tenth of a second 1–4 ds (=0.1–0.4 s): The length of a single blink of an eye [14]
The inverse second or reciprocal second (s −1), also called per second, is a unit defined as the multiplicative inverse of the second (a unit of time). It is applicable for physical quantities of dimension reciprocal time , such as frequency and strain rate .
Its SI unit is the reciprocal seconds (s −1); other common units of measurement include the hertz (Hz), cycles per second (cps), and revolutions per minute (rpm). [ 1 ] [ a ] [ b ] Rotational frequency can be obtained dividing angular frequency , ω, by a full turn (2 π radians ): ν =ω/(2π rad).
The solar flux unit is a unit of spectral irradiance equal to 10 −22 W⋅m −2 ⋅Hz −1 (100 yW⋅m −2 ⋅Hz −1). The nox (nx) is a unit of illuminance equal to 1 millilux ( 1 mlx ). The nit (nt) is a unit of luminance equal to one candela per metre squared ( 1 cd⋅m −2 ).
The SI has special names for 22 of these coherent derived units (for example, hertz, the SI unit of measurement of frequency), but the rest merely reflect their derivation: for example, the square metre (m 2), the SI derived unit of area; and the kilogram per cubic metre (kg/m 3 or kg⋅m −3), the SI derived unit of density.
At 20 °C (68 °F), the speed of sound in air, is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.91 s or one mile in 4.69 s. It depends strongly on temperature as well as the medium through which a sound wave is propagating.