how fast is the speed of light in a vacuum
Speed of light The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its exact value is 7008299792458000000♠299,792,458 metres per second (approximately 300,000 km/s (186,000 mi/s)[Note 3]). It is exact because by international agreement a metre is defined to be the length of the path travelled by light in vacuum during a time interval of 1/299792458 second.[Note 4][3] According to special relativity, c is the maximum speed at which all conventional matter and hence all known forms of information in the universe can travel. Though this speed is most commonly associated with light, it is in fact the speed at which all massless particles and changes of the associated fields travel in vacuum (including electromagnetic radiation and gravitational waves). Such particles and waves travel at c regardless of the motion of the source or the inertial reference frame of the observer. In the special and general theories of relativity, c interrelates space and time, and also appears in the famous equation of mass–energy equivalence E = mc2.[4]
Metre per second squared As acceleration, the unit is interpreted physically as change in velocity or speed per time interval, i.e. metre per second per second and is treated as a vector quantity.
Limit of a function (the Dirichlet function) has no limit at any x-coordinate.
g-force Human tolerances depend on the magnitude of the g-force, the length of time it is applied, the direction it acts, the location of application, and the posture of the body.[7][8]:350