The state equation of a new matter is
$$
p=A T^3 / V,
$$
where $p, V$ and $T$ are the pressure, volume and temperature, respectively, $A$ is a constant. The internal energy of the matter is
$$
U=B T^n \ln \left(V / V_0\right)+f(T),
$$
where $B, n$ and $V_0$ are all constants, $f(T)$ only depends on the temperature. Find $B$ and $n$.