The discussion revolves around the simplification of a force and couple system as depicted in a series of figures. Participants are examining the implications of taking moments about a pivot point in a static scenario involving a rotating bar and applied forces.
Some participants have offered clarifications about the static nature of the diagrams and the concept of couples in the system. There is an ongoing exploration of the definitions and implications of pivot points and moments, with no explicit consensus reached on the interpretations presented.
Participants are navigating the complexities of the problem setup, including the representation of forces and the assumptions about the pivot point's location. The discussion reflects a need for deeper understanding of the static conditions described in the textbook.
You're confused because you've jumped over a couple of steps.goldfish9776 said:
the diagram 4-35c is confusing , it shows the point B is moving ... It should show point A is moving , right ? Since B is the pivot ...SteamKing said:
You're still confused. Nothing is moving. The straight arrows merely indicate the direction of the force vectors. The curly arrows are there to indicate that a couple is present and the direction (CW or CCW) of the moment.goldfish9776 said:
Ok, the f at point a cancel off -f at point b , causing the moment to occur at point b ...but the text gives taking moment about point b , doesn't it means the pivot is situated at point b ?SteamKing said:
Yes. The point is, the couple can be positioned anywhere along the length of the rod.goldfish9776 said:
It depends what you mean by a pivot. If you are thinking of it as the stick undergoing an actual rotation as a result of these applied forces, with the pivot being the point that remains stationary, you have no idea where the pivot will be. It depends on the mass distribution along the stick.goldfish9776 said:
