Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mechanical Model for Relativistic Blast Waves   Relativistic blast waves can be described by a mechanical model. In this
model, the "blast" -- the compressed gas between the forward and reverse shocks
-- is viewed as one hot body. Equations governing its dynamics are derived from
conservation of mass, energy, and momentum. Simple analytical solutions are
obtained in the two limiting cases of ultra-relativistic and non-relativistic
reverse shock. Equations are derived for the general explosion problem.

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The categories of this paper are: nucl-th
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The categories of this paper are: funct-an
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The categories of this paper are: stat
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The categories of this paper are: eess
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The categories of this paper are: econ
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: cs
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph