Just curious if this was the right way to do this problem. A tire is going at 180 rev/min. There is a rock in the tire (on the outside) and the tire has a radius of .5 meters. What is the speed and acceleration of the rock? 180 rev/min = 3 rev / s 3 rev/s means its going 3 circumferences every second so thats 2(3.14)(.5) which is 3.14*3. So the rock is going 9.42 m/s for the speed. Then the acceleration is centripetal which is 9.42^2/.5?