21 meters per second in miles per hour

Conversion

21 meters per second is equivalent to 46.9756621331424 miles per hour.^[1]

Conversion in the opposite direction

The inverse of the conversion factor is that 1 mile per hour is equal to 0.021287619047619 times 21 meters per second.

It can also be expressed as: 21 meters per second is equal to $\frac{1}{0.021287619047619}$ miles per hour.

Approximation

An approximate numerical result would be: twenty-one meters per second is about forty-six point nine seven miles per hour, or alternatively, a mile per hour is about zero point zero two times twenty-one meters per second.

Units involved

This is how the units in this conversion are defined:

Meters Per Second

"Meter per second is an SI derived unit of both speed (scalar) and velocity (vector quantity which specifies both magnitude and a specific direction), defined by distance in metres divided by time in seconds.The SI unit symbols are m·s−1, m s−1, m/s, or m/s, sometimes (unofficially) abbreviated as mps. Where metres per second are several orders of magnitude too slow to be convenient, such as in astronomical measurements, velocities may be given in kilometres per second, where 1 km/s is 1000 metres per second, sometimes unofficially abbreviated as kps."

Wikipedia page of meters per second

Miles Per Hour

"Miles per hour (abbreviated mph, MPH or mi/h) is an imperial and United States customary unit of speed expressing the number of statute miles covered in one hour. Although kilometres per hour is now the most widely used measure of speed, miles per hour remains the standard unit for speed limits in the United States, the United Kingdom, Antigua & Barbuda and Puerto Rico, although the latter two use kilometres for long distances."

Wikipedia page of miles per hour

Footnotes

[1] The precision is 15 significant digits (fourteen digits to the right of the decimal point).

Results may contain small errors due to the use of floating point arithmetic.