1. The problem statement, all variables and given/known data A particle moving along a straight line with constant acceleration starts its motion at t = 0. The particle is observed to change direction at t=4s, and when t=10s it reaches the position of -2 m with a velocity of -2.4 m/s measured from a chosen reference frame. Find the position of the particle when it changes direction of motion. Answer: 5.2 m 2. Relevant equations x = x0 + v0*t + (1/2)at^2 v = v0 + at and possibly: v^2 = v0^2 + 2a(x-x0) 3. The attempt at a solution I'm not really sure how to go about doing this problem. I'm getting a little confused on the defining variables part even -- this is what I THINK they should be defined as but I'm not sure: x = -2 m at t=10 x0 = ? v = 0 m/s at t=4s, -2.4 m/s at t=10 v0 = ? a = ? It seems like I'm missing 3 things. I'm thinking either v0 or x0 is 0, but I'm not sure which of those is 0. I think I'll only be using the first 2 equations since time is involved, and that's really as far as I got on this problem. :( Any help is appreciated, I have a quiz that includes this problem due tomorrow at 1:25 PM eastern time.