1. The problem statement, all variables and given/known data Okay, wordy. Read through though, plz The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows uniformly with an acceleration of -5.60 m/s^2 for 4.20s, making straight skid marks 62.4m long ending at the tree. At what speed does it hit the tree? 2. Relevant equations Vf=Vi+at 3. The attempt at a solution So I saw I had a=-5.60m/s^2, t=4.20s, xf=62.4m, and Vf=0 (since after he hit the tree, he stopped). So I plugged them into Vf=Vi+at (or rather Vi=Vf-at), or 0-(-5.60)*4.20, to give 23.52 m/s. It seems wrong, though. Suggestions or advice?