In special relativity, four-acceleration is a four-vector. The four-acceleration of the four-vector a is defined as the change in four-velocity over the particle's own time:
... census of 2000, there are 16,146 people, 5,480 households, and 4,197 families residing in the town. The population density is 1,058.4/km² (2,740.4/mi²). There ...