We read that the a couple is a free vector, i.e it does not depend on the point of application. However, please consider the following example: If you apply two equal magnitude forces anti-parallel to each other, one on each side of the wheel, a couple is formed, and so the wheel will rotate about the axis as expected. Now if take this couple and move it elsewhere (e.g., not at the wheel axis), the wheel will not turn in the same way, even though we did not change the magnitude or the direction of the couple moment. This implies that the external effect of a couple does depend on its point of application. What am I missing? How do we resolve this apparent contradiction? Thanks very much for all your help! Kevin P.S. This is my first post on this forum.