

Today in class we covered problem 6/216 on page 72 of the notes. Dr. Krousgrill said in class that the angular acceleration when the rod and disk are at the point shown is zero. I agree with that.
However, he said that this means that angular acceleration was then zero for all time. Was he referring to the angular acceleration of the rod/linkage combination? Or was he talking about the disk rotating on it's pin joint on the linkage?
If angular acceleration was zero for all time, how did the disk/linkage combination start moving and obtain a rotational velocity?
Thanks
Alex Taylor