Q$6(60$ pts$)$: A bar of mass $\backslash ($ M $\backslash )$ and length $\backslash ($ L $\backslash )$ has an axel going through one end of the bar. The radius of the axel is $\backslash ($ r $\backslash ).$ When the bar pivots about this axel, there is a small amount of constant friction $\backslash ($ f $\backslash )$ between the axel and the bar. The bar is initially held vertically. You then let go$,$ and the bar swings around. You measure the angular speed $\backslash (\backslash$omega$\_\{\backslash$mathrm$\{$f$\}\}\backslash )$ of the bar as it reaches the bottom. Use this information to find frictional force between the bar and the axel. The moment of inertia of a bar spun around one end is $\backslash ($ I$=\backslash$frac$\{1\}\{3\}$ M L$^\{2\}\backslash ).$