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Spastic, where I think you and the NCEES solution are wrong is that you can't say that the horizontal force on the block is 4.4x the horizontal force in the chain. The reason for this is that the friction force (which is a vertical force) produces a moment in the same direction as the vertical component of the chain tension. You might think at a glance the moments they produce cancel each other out since the distance from the point the chain attaches to the surface of the clamp on the block is the same at 13 inches, but they do not because of their directions.

See my free-body diagrams of one of the members of the clamp attached and you should be able to see that uN produces a moment in the same direction as the chain force. You actually don't even need to know the weight of the block to obtain the answer jonjjj and myself got. You can also check out a similar problem on slides 11 and 12 from this slide share.

[ATTACH]9322[/ATTACH]

<blockquote data-quote="J_MEC" data-source="post: 7413363" data-attributes="member: 23333">Spastic, where I think you and the NCEES solution are wrong is that you can&#039;t say that the horizontal force on the block is 4.4x the horizontal force in the chain. The reason for this is that the friction force (which is a vertical force) produces a moment in the same direction as the vertical component of the chain tension. You might think at a glance the moments they produce cancel each other out since the distance from the point the chain attaches to the surface of the clamp on the block is the same at 13 inches, but they do not because of their directions.See my free-body diagrams of one of the members of the clamp attached and you should be able to see that uN produces a moment in the same direction as the chain force. You actually don&#039;t even need to know the weight of the block to obtain the answer jonjjj and myself got. You can also check out a similar problem on slides 11 and 12 from this slide share.[ATTACH]9322[/ATTACH]</blockquote>

[QUOTE="J_MEC, post: 7413363, member: 23333"] Spastic, where I think you and the NCEES solution are wrong is that you can't say that the horizontal force on the block is 4.4x the horizontal force in the chain. The reason for this is that the friction force (which is a vertical force) produces a moment in the same direction as the vertical component of the chain tension. You might think at a glance the moments they produce cancel each other out since the distance from the point the chain attaches to the surface of the clamp on the block is the same at 13 inches, but they do not because of their directions. See my free-body diagrams of one of the members of the clamp attached and you should be able to see that uN produces a moment in the same direction as the chain force. You actually don't even need to know the weight of the block to obtain the answer jonjjj and myself got. You can also check out a similar problem on slides 11 and 12 from this slide share. [ATTACH]9322[/ATTACH] [/QUOTE]

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