Hello, I apologize if this question appears simple; it may be but I cannot find the answer in any of my textbooks. I want to turn a shaft with a diameter, d, and length, L, which has a plate attached at the end, of diameter D. I made up a side view of what I'm trying to illustrate in MSPaint as attached (shaft holder.png) I need to be able to rotate this at the free end of the shaft at 100 RPM, and my plan is to attach a sprocket at that end, link it with a chain, and have another sprocket connected to a motor. My question is, how much torque should I need to rotate this given the following parameters? I'm not sure where to begin; I tried to analyze this as a problem with a circular shaft and a weight at the end, and also I've tried using the polar moment of inertia of the shaft but it's leading me nowhere! please help!