21 feet per second in meters per second

Conversion

21 feet per second is equivalent to 6.4008 meters per second.^[1]

Conversion in the opposite direction

The inverse of the conversion factor is that 1 meter per second is equal to 0.156230471191101 times 21 feet per second.

It can also be expressed as: 21 feet per second is equal to $\frac{1}{0.156230471191101}$ meters per second.

Approximation

An approximate numerical result would be: twenty-one feet per second is about six point four zero meters per second, or alternatively, a meter per second is about zero point one six times twenty-one feet per second.

Units involved

This is how the units in this conversion are defined:

Feet Per Second

'The foot per second (plural feet per second) is a unit of both speed (scalar) and velocity (vector quantity, which includes direction). It expresses the distance in feet (ft) traveled or displaced, divided by the time in seconds (s, or sec). The corresponding unit in the International System of Units (SI) is the metre per second.Abbreviations include ft/s, ft/sec and fps, and the rarely used scientific notation ft s−1.'

Wikipedia page of feet per second

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.