here's the problem: which vectors follow the same path as R=ti + t^2j? The speed along the path may be different. (a) 2ti + 2t^2j (b) 2ti + 4t^2j (c) -ti + t^2j (d) t^3i + t^6j I think the answer is (a) and (b), and then (c) is in the opposite direction. I believe this because the velocities of (a) and (b) are (a): v=2 + 4t and (b): v=2 + 8t which is similar to the original: v=1+2t. (c): v=-1 + 2t is negative so it is in the opposite direction. am I correct or at least on the right train of thought? thanks!