- #1
Cyrus
- 3,238
- 17
I gota problem with the fixed collar on a smooth rod. The collar is like a rigid metal T shapped pipe, and the top of the t is where the shaft of the rod goes through. (Its in any basic statics book). It says this type of set up has a normal force perpendicular to the axis of the rod, (OK that's fine I get it), and a moment. (OK, I get that too, its restraining the rotation since its RIGID and not pin.) But the problem is HOW!? does it prevent moment!
To me, the only way to prevent moment is to have a counter moment produced where the collar meets the rod, in the top horizontal part of the T. This could be acomplished by a symmetrical distributive loading on opposite ends. ( See pic.) But the problem is that damm normal force. If you have a distributive loading like that, which kind of makes sense, because if its a very GOOD, or better yet IDEAL rod/collar, there is almost no slop between the two, and no friction. So this means that the area in contact on the top and bottom of opposing sides should be equal and opposite, so that a couple is produced. Also, one would expect the force to be maxium on the outer edges, and deminish as you approach the center. But then what about the normal force!? It is pointing up! This is distrubing becuase if a couple is acting on that part of the collar, you would expect to have zero force at its center, and most of the force along the edges. I don't know anymore...sigh...
To me, the only way to prevent moment is to have a counter moment produced where the collar meets the rod, in the top horizontal part of the T. This could be acomplished by a symmetrical distributive loading on opposite ends. ( See pic.) But the problem is that damm normal force. If you have a distributive loading like that, which kind of makes sense, because if its a very GOOD, or better yet IDEAL rod/collar, there is almost no slop between the two, and no friction. So this means that the area in contact on the top and bottom of opposing sides should be equal and opposite, so that a couple is produced. Also, one would expect the force to be maxium on the outer edges, and deminish as you approach the center. But then what about the normal force!? It is pointing up! This is distrubing becuase if a couple is acting on that part of the collar, you would expect to have zero force at its center, and most of the force along the edges. I don't know anymore...sigh...
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