is the proper time. In standard inertial coordinates, proper acceleration is the rate of change of proper velocity with respect to coordinate time.
Aμ=dUμdτcap A raised to the mu power equals the fraction with numerator d cap U raised to the mu power and denominator d tau end-fraction Uμcap U raised to the mu power is the four-velocity and
It consists of four components: one temporal and three spatial.
The (e.g., Physics, Sports Training, or a specific Software)?
: This is the physical acceleration experienced by an observer (e.g., the "g-force" felt by an astronaut). It is the acceleration relative to a free-fall, inertial observer who is momentarily at rest relative to the object. The Four-Vector ( Aμcap A raised to the mu power ) :