1. The problem statement, all variables and given/known data Hi again ,, my second one is easy: A tire 0.5 m in radius rotates at a constant rate of 200 rev/min. Find the speed and acceleration of a small stone stuck on the surface of the tire (on its outer edge). 2. Relevant equations 3. The attempt at a solution the Speed of the rock is easy to get (W=200 rev/min = (20*pi)/3 rad/s = (10*pi)/3 m/s) about the acceleration : should I get the tangent acceleration or the radial ??