Part B $-$ Platform Diving approximately how many revolutions will he make before striking the water after falling $\backslash ($ h$=24\mathrm{.}6\backslash$mathrm$\{$ft$\}\backslash )?$

Express your answer to three significant figures.

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The diver will complete

revolutions.

Part C $-$ Friction

A hand$-$brake system is used to stop a drum, as shown in the figure.

$($Figure $4)$

The drum has a mass of $100$ kg and a radius of gyration about the pin at $\backslash ($ O $\backslash )$ of $\backslash ($ k$\_\{$O$\}=0\mathrm{.}230\backslash$mathrm$\{$~m$\}\backslash ).$ The coefficient of friction between the brake pad and drum is $\backslash (\backslash$mu$\_\{$k$\}=0\mathrm{.}60\backslash ).$

Express your answer to three significant figures and include the appropriate units.

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$\backslash [$

h$=$

$\backslash ]$