I'm studying Analytical Mechanics, and in the section about the kinematics of rigid body, it is mentioned the following concepts:
- Center of rotation
- a reference position that is fixed with respect to the body
What is the definition of center of rotation, and how to find it ?
Secondly, any point on the body is fixed with respect to that body; on Earth, every point on the planet seems fixed, so do they mean any point on the rigid body by the second item ?