Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kinematic relative velocity with respect to stationary observers in
  Schwarzschild spacetime   We study the kinematic relative velocity of general test particles with
respect to stationary observers (using spherical coordinates) in Schwarzschild
spacetime, obtaining that its modulus does not depend on the observer, unlike
Fermi, spectroscopic and astrometric relative velocities. We study some
fundamental particular cases, generalizing some results given in other work
about stationary and radial free-falling test particles. Moreover, we give a
new result about test particles with circular geodesic orbits: the modulus of
their kinematic relative velocity with respect to any stationary observer
depends only on the radius of the circular orbit, and so, it remains constant.

22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph