\text { For an axially loaded rod, prove that } \beta=1 \text { for the } E^{\beta} / \rho \text { guidelines in Fig. 2-16. }
For stiffness, k=A E / l \Rightarrow A=k l / E For mass, m=A l \rho=(k l / E) l \rho=k l^{2} \rho / E
\text { So, } \quad f_{3}(M)=\rho / E, \text { and maximize } E / \rho \text {. Thus, } \beta=1 \text {. . }