I am stuck on a problem from the 5 Steps to a 5: AP Physics B&C book and would really appreciate anyone's help. 1. The problem statement, all variables and given/known data Determine (a) the acceleration of the block down the plane and (b) the time for the block to slide to the bottom of the plane. http://02.edu-cdn.com/files/static/mcgrawhillprof/9780071623209/INCLINED_PLANES_08.GIF [Broken] 2. Relevant equations F=ma F, gravity = mg F, friction = umg Kinematic equation ??? 3. The attempt at a solution Fx, up the plane = mgsin25 + umgcos25 = 204 N a = F/m = 204/30 = 6.8 m/s^2 Fx, down the plane = mgsin25 - umgcos25 = 44 N a = F/m = 44/30 = 1.5 m/s^2 I tried using x = Vot + 1/2 at^2 (x = 20 m, Vo = 3m/s) and v = Vo + at (v = 0, Vo = 3 m/s) to solve for time, but my answers were way off on both attempts.