21 miles per hour in meters per second

Conversion

21 miles per hour is equivalent to 9.38784 meters per second.^[1]

Conversion in the opposite direction

The inverse of the conversion factor is that 1 meter per second is equal to 0.106520775812114 times 21 miles per hour.

It can also be expressed as: 21 miles per hour is equal to $\frac{1}{0.106520775812114}$ meters per second.

Approximation

An approximate numerical result would be: twenty-one miles per hour is about nine point three nine meters per second, or alternatively, a meter per second is about zero point one one times twenty-one miles per hour.

Units involved

This is how the units in this conversion are defined:

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

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

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.