I've heard "one nano for one foot" but never checked it out. Let's do that now: 1 mile = 5,280 feet Speed of light = 186,282 miles per second = (186,282 x 5,280) = 983,568,960 feet per second. One nanosecond = 1 x 10-9 second. Speed of light = 0.9835+ feet per nanosecond You asked for the reciprocal = 1.0167 ns per foot (rounded) It looks like "one nano for one foot" is a pretty good approximation ! If given speed of light in terms of meters first: 299,732,458 m/s (100cm/1m)(1"/2.54cm)(1'/12")(10^-9) > we get (after canceling units) .983374206 1'/s >we need the answer in s not 1/s so we take the reciprocal: (.983374206 1'/s) -1 >we have now satisfied the problem with a solution of 1.01690688 ns/1' My answer is not rounded because of significant digits The units in the conversion above were exact so we should use the 9 significant digits we started with. (please correct if needed)
The speed of light in vacuum corresponds to 299.8 millimeters, or 11.8 inches, per nanosecond.
As engineers, expected to be able to recognize and work with "close enough" figures,
we often use "1 nanosecond = 1 foot."
In a vacuum, it travels 299.792458 millimeters
That's 11.8 inches, and one handy rule that engineers often keep
on their approximate thumb is " 1 ns = 1 foot ."
A beam of light travels 5 feet in one nanosecond.
Light travels 299.792458 millimeters in 1 nanosecond
Here's a handy mnemonic: "1 light-nanosecond = 1 foot" is only about 1.6% off.
In a vacuum, light will travel 300,000 km per second. "On Earth"... well, it really depends what light travels through. In air, it would go almost as fast as in a vacuum.
It would travel approx 300,000,000 metres, except that this distance is far greater than the size of the earth.
1 light nanosecond = 0.299792458 meter
983,568,980 feet per seconds
1 day = 8.64e13 nanoseconds.
1 second = 1 billion nanoseconds 4 seconds = 4 billion nanoseconds = 4,000,000,000 = 4 x 109
10000000000000000
60,000,000,000
1 minute = 60 seconds 5 minutes = 300 seconds = 300 billion nanoseconds
It takes 1.3 to 1.4 nanoseconds for light to travel 1 foot.
The Earth is 500 light-seconds from the Sun. One second is 10^9 nanoseconds.
Light in a vacuum travels at 300,000 km per second. It will take distance divided by speed time to travel. Or 30 million thousand km divided by 300 thousand km/s = 100 000 seconds. This is 27.8 hours.
473,099,999,999,999,936 nanoseconds.
Since a microsecond is a millionth of a second, just divide the distance light travels in one second, by a million.
3.1536E+24 nanoseconds.
5.9327x10 ^19 nanoseconds
1 microsecond = 1,000 nanoseconds.
Six years = 1.89216e17 nanoseconds.
1 second = 1000000000 nanoseconds
9.5 years = 299,629,999,999,999,936 nanoseconds.
20,000,000,000 nanoseconds = ~0.333 minutes.