# Mechanical Engineering - Thermodynamics

Exercise : Thermodynamics - Section 2
31.
The general gas energy equation is (where Q1 - 2 = Heat supplied, dU = Change in internal energy, and W1 - 2 = Work done in heat units)
Q1 - 2 = dU + W1 - 2
Q1 - 2 = dU - W1 - 2
Q1 - 2 = dU/W1 - 2
Q1 - 2 = dU x W1 - 2
Explanation:
No answer description is available. Let's discuss.

32.
The compression ratio for Diesel engines is
3 to 6
5 to 8
15 to 20
20 to 30
Explanation:
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33.
In an isothermal process,
there is no change in temperature
there is no change in enthalpy
there is no change in internal energy
all of these
Explanation:
No answer description is available. Let's discuss.

34.
Which of the following is the correct statement of the second law of thermodynamics?
It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work.
It is impossible to transfer heat from a body at a lower temperature to a higher temperature, without the aid of an external source.
There is a definite amount of mechanical energy, which can be obtained from a given quantity of heat energy.
all of the above