👉 A semi-rotary (or semi-rotational) object is an object that rotates through a fixed angle relative to its axis of rotation. This means that the object remains stationary relative to its original position, but the rotation causes it to move in a circular path around its axis. For example, if you have a bookshelf that is rotating clockwise when you hold it at different angles, the rotation affects both the height and width of the bookshelf. The bookshelf will remain stationary relative to
