In the parallel theorem, the 2nd axis must be within the body so tht the body cant turn about itsCMaxis rite .

Question

Thank you, Steve, Phillip. If my question is correct, I am not confused anymore. In some books use E=1/2(Icm+Md>2) to give E(rolling)=E(rotational,CM)+E(translational). In my humble understanding, it is not a good way because the body turns about CM, the parallel theorem is not applied. By accident, the coincidence happens only!The explanation must be vice versa. In some case, for example, the circular motion of a particle also gives 1/2mv(squared)=1/2mr(squared)w(squared) by accident. However, the circular motion is different from the rotational. Right?
Thank you all for sharing with me, especially for Steve's sharing.

Answer 1

The second axis is placed in any place, the only restriction to this is not to pass through the CM. You can put it also outside the body.

Answer 2

I hate it when that happens.