u denotes internal energy;
v denotes specific volume;
T denotes temperature.
Re: Thermodynamics, basic difficulty: How do I find u, when I know v and T at a state
From that information, you can't. You want the find internal energy but all you know is specific volume, which is volume per unit mass, meaning you don't know the total mass.
If you did, however, you can find U by integrating Cv(T)dT from T=0 to current T.
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