Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamics, entropy and waterwheels   In this paper the analogy between a thermal engine and a waterwheel is
developed in details, showing that the analogous of the flow of water in an
hydraulic engine is the flow of entropy in a thermal one. This analogy mat
serve to analyse in details the aspects of a thermal engine that are quite
distant from pupils' intuition. The discussion is complemented by an
illustration of the working of thermal and hydraulic engines at the microscopic
level, thus furnishing a view of what heat and work are at this level, and
introducing the statistical and information aspects of entropy. Both hydraulic
and thermal non-ideal engines are also discussed.

20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio