There is a $250-$m$-$high cliff at Half Dome in Yosemite National Park in California. Suppose a boulder breaks loose from the top of this cliff. $($a$)$ How fast will it be going when it strikes the ground? $($b$)$ Assuming a reaction time of $0\mathrm{.}300$ s$,$ how long will a tourist at the bottom have to get out of the way after hearing the sound of the rock breaking loose $($neglecting the height of the tourist, which would become negligible anyway if hit$)?$ The speed of sound is $335$ m$/$s on this day.