Relativistic speed

Relativistic effects are those discrepancies between values calculated by models considering and not considering relativity.

Speed is a scalar, being the magnitude of the velocity vector which in relativity is the four-velocity and in three-dimension Euclidean space a three-velocity.

Non-relativistic discrepancies include cosine error which occurs in speed detection devices when only one scalar component of the three-velocity is measured and the Doppler effect which may affect observations of wavelength and frequency.

Relativistic effects are highly non-linear and for everyday purposes are insignificant because the Newtonian model closely approximates the relativity model.

In special relativity the Lorentz factor is a measure of time dilation, length contraction and the relativistic mass increase of a moving object.

Lorentz factor , γ, as a function of speed, v . Its initial value is 1 when speed is zero and increases without bound as speed approaches light speed, c .
Inverse of Lorentz factor as a function of speed, v , as a proportion of light speed, c - a circular arc.