Speed Of Light to Feet Per Second (c to ft/s)

1 speed of light equals 983,571,056.4 feet per second (rounded).

1 speed of light = 983,571,056.4 feet per second

How to convert speed of light to feet per second

To convert speed of light to feet per second, multiply the number of speed of light by 983,571,056.4. The factor is rounded to 10 significant digits. To go the other way, multiply feet per second by 1.016703362×10⁻⁹ (rounded).

feet per second = speed of light × 983,571,056.4

Example: 10 speed of light = 9,835,710,564 feet per second.

About these units

Speed Of Light (c)

ScientificCurrent unit

Exactly 299,792,458 m/s, the speed of light in a vacuum and the fundamental constant that defines the meter.

Light was once thought to arrive instantly. In 1676 Ole Rømer timed eclipses of Jupiter's moon Io and concluded that light takes about 22 minutes to cross Earth's orbit. In 1729 James Bradley used the aberration of starlight to estimate about 8 minutes 12 seconds from Sun to Earth. Later experimenters used a toothed wheel (Fizeau), a rotating mirror (Foucault), and in 1930 to 1935 Michelson, Pease and Pearson used a mile-long vacuum chamber. The letter c is itself uncertain: it may stand for constant or the Latin celeritas, swiftness, and Einstein switched to it in 1907.

Since 1983 the speed of light has been fixed at exactly 299,792,458 m/s, and the meter is defined as the distance light travels in a vacuum in 1/299,792,458 of a second. Measurement therefore became a matter of defining the constant, not of improving experiments. For scale, light takes about 1.3 seconds to travel from the Earth to the Moon, about 8.3 minutes from the Sun, and roughly one nanosecond to go a foot. James Clerk Maxwell showed in 1865 that light is an electromagnetic wave.

1 speed of light = 299,792,458 meters per second (exactly).

Sources: Wikipedia: Speed of light; NIST: the meter and the SI redefinition

Foot Per Second (ft/s)

US & ImperialCurrent unit

Exactly 0.3048 m/s. Used for velocity in US engineering, ballistics and fluid flow.

Compound units rarely have a recorded inventor, and the foot per second is a plain example: it is just a foot divided by a second. The foot underneath it began as a body-based length ranging historically from about 250 to 335 millimeters, with ancient Greek and Roman feet near 300 mm. Before the SI arrived in 1960, feet per second, miles per hour and knots were more common than meters per second, depending on region.

The 1959 international agreement fixed the foot at exactly 0.3048 meter, so one foot per second is exactly 0.3048 m/s, about 1.097 km/h or 0.6818 mph. Sound moves at about 1,125 ft/s in dry air at 20 °C, which is 343 m/s. Chuck Yeager's Bell X-1 reached about 361 m/s in 1947, near 1,184 ft/s. The unit remains common in American engineering and science, where lengths are still given in feet and inches.

1 foot per second = 0.3048 meters per second (exactly).

Sources: Wikipedia: Foot per second; Wikipedia: Foot (unit); NIST Guide to the SI, Appendix B.8: conversion factors

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