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Walt Walt is offline
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First recorded activity by BoatBanter: Jul 2006
Posts: 348
Default Rope and Block Question #1

DSK wrote:

At what angle does the sheave load match the line load?
[1 pt]


Seems to me that the running part would have to be above horizontal for
the load on the sheave to match the load on the line.


Huh? Imagine a horizontal line with 1000 lbs of tension on it. It runs
through a block, but the block doesn't deflect the line at all. What's
the force on the block? Zero, right?

Now pull up on the block. As the angle of deflection increases, so does
the load on the block. Eventually it becomes twice the tension (assuming
the tension doesn't change as you change the delfection angle).
Somewhere in between 0 and 2T it equals T.

BTW, I love topological proofs, in case you haven't noticed already.

Or just imagine a bridle with a traveler block. If the angle of the
bridle is 120 degrees, the force on the block is equal to the tension on
the bridle.

//Walt