What is the exact speed of light?

Question

I want to no what the exact speed of light is in km/h and meters p/s
aswell as miles p/s

thanx

Answer 1

speed of light

n : the speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second [syn: light speed, {c}]

1 speed of light in vacuum is equal to:
Metric
kilometer per second 299792,5
meter per second 2,997925e+08
kilometer per hour 1,079253e+09
meter per minute 1,798755e+10
British And American
mile per second 186282,4
mile per hour 6,706166e+08
foot per second 9,83571e+08
For Runners and Joggers
minutes per kilometer 1,798755e+07
seconds per kilometer 299792,5
seconds per 100 metres 2997925
minutes per mile 1,117694e+07
seconds per mile 186282,4
seconds per 100 yards 3278570
Nautical
knot 5,827499e+08
sea mile per hour 5,827499e+08
Other
speed of sound in gas (mach) 881742,5

Answer 2

No, you would be moving at exactly the speed of light. The formula for adding speeds in relativity is: S=(V+U)/(1+V*U/C^2) Where: U is the speed of the train V is how fast you walk S is your speed as seen by someone standing by the track. C is the speed of light In your example the speed of the train is exactly the speed of light, so U=C So the formula simplifies to: S=(V+C)/(1+V*C/C^2) S=(V+C)/(1+V/C) Let us assume he walks really fast, at a tenth the speed of light. Then V=0.1C So S=(0.1*C+C)/(1+0.1*C/C) S=1.1*C/(1+0.1) S=1.1C/1.1 S=C So the person standing by the track sees the person walking on the train passing him at exactly C, and the train also passing at exactly C. In other words he sees the person not making any progress toward the front of the train at all. This odd, paradoxical result is one of the reasons scientists say nothing (except light itself) can actually go at exactly the speed of light. There are other reasons. Other formulas say time stops, distance shrinks to zero, and mass becomes infinite at exactly the speed of light. Since speed is distance divided by time, the walking man's speed would be 0 distance / 0 time, or 0/0. Dividing by 0 is not an allowed operation in math, which is one of many reasons relativity says nothing can go faster than light. Most people have trouble imagining all this or even believing it, but many experiments have proved the formula is correct at all speeds where experiments can be done. Of course the experiment cannot be one with the train actually going at speed C, but that does not make the formula wrong. That just means the experiments prove what is always said, that nothing can go faster than light.

Answer 3

In what? The speed varies very slightly according to the medium it is travelling in - another teensy detail the physics teachers omit to mention...

Mostly the speed is given as 'in vacuum' ie between the stars.

Answer 4

It the speed light cover a distance in a given time, in this instance hell of a fast

Answer 5

299 792 458 m/s

Answer 6

187,500 miles per second. (Thats based on the light taking 8 minutes to travel the 90,000,000 miles from the sun to the earth.)

Answer 7

186,262 mps. Thats 8 minutes to the sun, 1000 years to the next star system and 100,000 years across the galaxy. Have fun!!

Answer 8

186000 miles per second in vacuum slower in air, even slower in water and slower still in glass, so it does not appear to be a constant

Answer 9

It's exactly the same speed as dark.

Answer 10

Depends on how quick you switch the light on!