Search results
Results From The WOW.Com Content Network
To do this, they redefined the metre as "the length of the path traveled by light in vacuum during a time interval of 1/ 299 792 458 of a second". [93] As a result of this definition, the value of the speed of light in vacuum is exactly 299 792 458 m/s [163] [164] and has become a defined constant in the SI system of units. [13]
The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics.It is defined as the distance that light travels in free space in one second, and is equal to exactly 299 792 458 m (approximately 983 571 055 ft or 186 282 miles).
The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in vacuum c = 299 792 458 metres per second (approximately 1 079 000 000 km/h or 671 000 000 mph). Matter cannot quite reach the speed of light, as this would require an infinite amount of energy.
The product of Simon Newcomb's J1900.0 mean tropical year of 31 556 925.9747 ephemeris seconds and a speed of light of 299 792.5 km/s produced a light-year of 9.460 530 × 10 15 m (rounded to the seven significant digits in the speed of light) found in several modern sources [10] [11] [12] was probably derived from an old source such as C. W ...
For example, the speed of light is defined as having the numerical value of 299 792 458 when expressed in the SI unit metres per second, and as having the numerical value of 1 when expressed in the natural units Planck length per Planck time. While its numerical value can be defined at will by the choice of units, the speed of light itself is a ...
≈ 1 hour walk, Currently defined in US as 3 Statute miles, [3] but historically varied from 2 to 9 km ≈ 4828 m: light-day: ... ≡ 299 792 458 m: light-year: ly
It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299 792 458 when expressed in the unit m⋅s −1, where the second is defined in terms of the caesium frequency Δν Cs. The metre may be expressed directly in terms of the defining constants: 1 m = 9 192 631 770 / 299 792 458 c / Δν Cs .
E / m = c 2 = (299 792 458 m/s) 2 = 89 875 517 873 681 764 J/kg (≈ 9.0 × 10 16 joules per kilogram). So the energy equivalent of one kilogram of mass is 89.9 petajoules; 25.0 billion kilowatt-hours (≈ 25,000 GW·h) 21.5 trillion kilocalories (≈ 21 Pcal) [note 4] 85.2 trillion BTUs [note 4] 0.0852 quads or the energy released by ...