My main confusion is in the proof my professor showed us just before break. He came up with a relationship of (angular acceleration)=radius*(linear acceleration) which doesnt make sense, we are assuming a 90 degree angle, so from r x (angular acceleration) = (linear acceleration) wouldnt we get r*aa=la --> aa=la/r. I am in need of this to make the conversion in a problem where I can estimate the velocity of an action (and derive the velocity from the acceleration). But have to start with the basic Fnet=Iaa, and the only force is the torque. Any clarification would be great. THANK YOU!