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Conversion of the Mach unit of speed depends on the altitude at which the speed is measured. That altitude should be specified either in feet (for example, |altitude_ft=10,000 ) or in metres (for example, |altitude_m=3,749 ).
exactly equal ≈ approximately equal to ≘ (exactly) corresponds to (different types of quantity describing the same phenomenon) digits: indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369...) (H) of chiefly historical interest
A femtosecond is a unit of time in the International System of Units (SI) equal to 10 −15 or 1 ⁄ 1 000 000 000 000 000 of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. [1] A femtosecond is to a second, as a second is to approximately 31.69 million years.
A use of the unit radian per second is in calculation of the power transmitted by a shaft. In the International System of Quantities (SI) and the International System of Units, widely used in physics and engineering, the power p is equal to the angular speed ω multiplied by the torque τ applied to the shaft: p = ω ⋅ τ.
By default, the output value is rounded to adjust its precision to match that of the input. An input such as 1234 is interpreted as 1234 ± 0.5, while 1200 is interpreted as 1200 ± 50, and the output value is displayed accordingly, taking into account the scale factor used in the conversion.
In SI units, the values of c, h, e and k B are exact and the values of ε 0 and G in SI units respectively have relative uncertainties of 1.6 × 10 −10 [16] and 2.2 × 10 −5. [17] Hence, the uncertainties in the SI values of the Planck units derive almost entirely from uncertainty in the SI value of G.
In physics, natural unit systems are measurement systems for which selected physical constants have been set to 1 through nondimensionalization of physical units.For example, the speed of light c may be set to 1, and it may then be omitted, equating mass and energy directly E = m rather than using c as a conversion factor in the typical mass–energy equivalence equation E = mc 2.
Speed is the magnitude of velocity (a vector), which indicates additionally the direction of motion. Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph).