1. The problem statement, all variables and given/known data A moving particle reaches its max. speed at the instant t = 3. (Before and after 3, its speed is less.) It follows that the particle's acceleration is 0 at the instant t = 3... Show that this is FALSE 2. Relevant equations v = dR/dt a = d^2 R / dt^2 3. The attempt at a solution How do I show this is false? The derivative of velocity is acceleration so I would think it's true and is indeed 0. This is on a chapter for vector analysis on acceleration and curvature.