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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).
The hertz is defined as one per second for periodic events. The International Committee for Weights and Measures defined the second as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom" [3] [4] and then adds: "It follows that the hyperfine splitting in the ground state of the ...
The scalar absolute value of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s −1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector.
Metric prefixes; Text Symbol Factor or; yotta Y 10 24: 1 000 000 000 000 000 000 000 000: zetta Z 10 21: 1 000 000 000 000 000 000 000: exa E 10 18: 1 000 000 000 000 000 000: peta P 10 15: 1 000 000 000 000 000: tera T
126.2326 Ms (1461 d 0 h 34 min 40 s): The elected term of the President of the United States or one Olympiad. 10 9: gigasecond Gs decades, centuries, millennia (1 Gs = over 31 years and 287 days = 1,000,000,000 s) 1.5 Gs: Unix time as of Jul 14 02:40:00 UTC 2017. Unix time being the number of seconds since 1970-01-01T00:00:00Z ignoring leap ...
For higher speeds up to about 100 km/h outside built-up areas, a similarly defined 2-second rule applies, which for 100 km/h translates to about 50 m. For speeds on the order of 100 km/h there is also the more or less equivalent rule that the stopping distance be the speed divided by 2 k/h, referred to as halber tacho ( half the speedometer ...
The knot (/ n ɒ t /) is a unit of speed equal to one nautical mile per hour, ... 0.51444 metres per second (approximately), 1.15078 miles per hour (approximately),
One example is represented by the conditions in the first 10 −43 seconds of our universe after the Big Bang, approximately 13.8 billion years ago. The four universal constants that, by definition, have a numeric value 1 when expressed in these units are: c, the speed of light in vacuum, G, the gravitational constant, ħ, the reduced Planck ...