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 $7800 \mathrm{~kg} / \mathrm{m}^{3}$.