I'm LOST!!!! Car is suppose to overtake truck but at what velocity? two cars C and D move in the same direction in parrallel lanes of a straight road. C starts from rest and begins to move with a constant acceleration. at that instat the C begins to move it is overtaken by D, which is moving with a constant speed of 6ms-1 !) it is given that C's acceleration remains constant the instant it overtakes D. this occurs 5seconds after c begins to move. Find C's speed at the instant when it overtakes D. now i know i should ignore how D overtook C and i believe that i should use s=vt-1/2at^2 but i dont get a number answer its always a variable with a number please someone help me.