A rock with mass $m$ slides with initial velocity $v_{0}$ on a horizontal surface. A retarding force $F_{R}$ that the surface exerts on the rock is proportional to the square root of the instantaneous velocity and position of the rock as a function of time. (b) In terms of $m, k,$ and $v_{0},$ at what time will the rock come to rest? (c) In terms of $m, k,$ and $v_{0}$ , what is the distance of the rock from its starting point when it comes to rest?