The expression of the time taken to swing the pendulum is,
[tex]T(L)=2\pi\sqrt[]{\frac{L}{32}}[/tex]Part (a)
Substitute the known values in the expression of time.
[tex]\begin{gathered} T(L)=2(3.14)\sqrt[]{\frac{6}{32}} \\ =(6.28)(0.433) \\ \approx2.72\text{ s} \end{gathered}[/tex]Thus, the time taken by pendulum to complete one swing is 2.72 s.
Part (b)
Convert the length of pendulum in feet as,
[tex]\begin{gathered} 9\text{ in=}(9\text{ in)(}\frac{1\text{ ft}}{12\text{ in}})_{} \\ =0.75\text{ ft} \end{gathered}[/tex]Substitute the known values in the expression of time.
[tex]\begin{gathered} T(L)=2(3.14)\sqrt[]{\frac{0.75}{32}} \\ =(6.28)(0.153) \\ \approx1.0\text{ s} \end{gathered}[/tex]Thus, the time taken by pendulum to complete one swing is 1.0 s.