Consider a uniform bar, of length 1 m, Young's modulus 125 Gpa, and density of \( 1,728 \mathrm{~kg} / \mathrm{m}^{3} \) with a free-free boundary condition, as shown in the figure.
\[
[k]=\frac{E A}{l}\left[\begin{array}{rr}
1 & -1 \\
-1 & 1
\end{array}\right][m]=\frac{\rho A l}{6}\left[\begin{array}{ll}
2 & 1 \\
1 & 2
\end{array}\right]
\]
Find the first bending natural frequency ( \( \mathrm{rad} / \mathrm{s}) \) of the bar using a single bar element.
