Solution. We know that: Density $=\frac{\text { Mass }}{\text { Volume }}$
$$
\begin{array}{l}
=\frac{15600 \mathrm{~kg}}{2 \mathrm{~m}^{3}} \\
=7800 \mathrm{~kg} / \mathrm{m}^{3}
\end{array}
$$
Thus, the density of steel in SI units is $7800 \mathrm{~kg} / \mathrm{m}^{3}$.