Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Classical and relativistic conservation of momentum flux in
  radio-galaxies   A new set of laws of motion for turbulent jets propagating in an
intergalactic medium characterized by a decreasing density is derived by
applying conservation of momentum flux both in the classical and relativistic
framework. Two characteristic features of radio-galaxies, such as oscillations
and curvature, are modeled by a classical helicoidal jet. A third feature of a
radio-galaxy, the appearance of knots, is explained as an effect due to the
theory of images.

35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin