1. The problem statement, all variables and given/known data I'd just like someone to see if I answered correctly. I'm having a bit of difficulty grasping the vagueness of the displacement in these questions I've been getting in my textbook. From what I gather the displacement is relative to the vector points, (the two x points in kinematic equations). However, how am I to know what direction the car is travelling relative to the x plane if it doesn't specify the point in a question? I don't know if you guys get me.. The acceleration I found in the question below, could be positive or negative, it doesn't specify enough. Or am I wrong? A car slows down from 23 m/s to rest in a distance of 85 m. What was its acceleration, assumed constant? 2. Relevant equations The kinematic equations for constant acceleration. I attempted to solve it with the following: finalV^2=initialV^2+2a(finalX-initialX) 3. The attempt at a solution Here is an image of my attempted work. I got -3.1 m/s^2 as my answer.