The vertical distance covered by freely falling feather is,
[tex]h=ut+\frac{1}{2}at^2[/tex]Since the feather is falling freely then the initial speed of feather is zero.
Plug in the known values,
[tex]\begin{gathered} 6.87\text{ m=(0 m/s)t+}\frac{1}{2}a(1.32s)^2 \\ a=\frac{2(6.87\text{ m)}}{(1.32s)^2} \\ \approx\text{7}.89m/s^2 \end{gathered}[/tex]Therefore, the free fall acceleration of the feather is 7.89 m/s2.
The speed of the feather at the bottom of the crater is,
[tex]v=u+at[/tex]Substitute the known values,
[tex]\begin{gathered} v=0m/s+(7.89m/s^2)(1.32\text{ s)} \\ \approx10.4\text{ m/s} \end{gathered}[/tex]Therefore, the speed of feather with which it strikes on the bottom of the crater is 10.4 m/s.