Nonuniform/Uniform Circular Motion... i think I keep putting my posts in the wrong forum. Anyway.. I have a few problems left that I'm completely stumped on how to do. #1) A typical lab centrifuge rotates at 4000rpm. Test tubes have to be placed into a centrifuge very carefully because of the very large accelerations. What is the acceleration at the end of a test tube that is 10cm from the axis of rotation in? Out of my 6, these trouble me the most. For #1, I made the radius 10cm, the velocity constant, but am unsure what equations I need to plug those in.