Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Acoustic force of the gravitational type   In this paper it was shown that, under certain restrictive conditions,
Bjerknes secondary forces are attractive and proportionate to the product of
the virtual masses of the two bubbles.

33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas