Table 2.9.5(a) lists the information given in the statement of the example.

Since $v$ is constant, $\stackrel{\.}{v}\=0$, so $\mathbf{a}\=\stackrel{\.}{v} \mathbf{T}\+\mathrm{\κ} v^2 \mathbf{N}$ reduces to $\mathbf{a}\=\mathrm{\κ} v^2 \mathbf{N}$. Hence,

 $∥\mathbf{F}∥\=m ∥\mathbf{a}∥\=m \mathrm{\κ} v^2$ = $\left(1\/16\right) \frac{2}{{\left(1\+4 x^2\right)}^{3\/2}} {\left(3\right)}^2$ = $\frac{9}{8{\left(1\+4 x^2\right)}^{3\/2}}$ 

is to be maximized. By inspection, the maximum of $9\/8$ occurs at $x\=0$.