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(Doug Miller) wrote in message om...
In article , (Harry K) wrote:
(Doug Miller) wrote in message
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In article ,
(Harry K) wrote:
(Doug Miller) wrote in message
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In article ,
(Harry K) wrote:
"Greg O" wrote in message
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"The Other Harry" wrote in message
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The question was (and is), what happens to the load?

If the entire pot arrangement weighs 40 pounds, does half
of that load go to the top hook and half of it go to the
anchor hook?

--
Harry

I am assuming you have a rope attached to the pot, that runs up to a
hook
or
pulley attached to the ceiling,, then back down to an cleat.
If the pot weighs 40 lbs, the top hook in the ceiling, (or window
frame,
whatever!) with the pulley will be carrying 80 lbs. The tension,
(weight)
felt by the rope at the cleat will be 40 lbs.
Greg

Wrong. The tension on both sides will be equal (20 lbs) and the top
hook will feel 40lbs. There is nothing being added to the 40 lbs to
increase it to 80. I think you have confused the effect of a pulley
which, when rigged right, will cut the lifting force by 1/2.

It appears that *you* are the confused one here. A *movable* pulley will
cut
the lifting force in half. A *fixed* pulley only changes the direction in
which the force is applied -- and this situation is entirely analogous to
a
fixed pulley.

--------40----top-------------
/\
/ \
20/ \20
/ \
load/40 \anchor
------------bottom-------

Nope. You have a major problem he on the left side, a 40-lb weight is
suspended on a rope that has only 20 lbs tension. Doesn't work that way.

Suppose the anchor on the right is replaced by an un-anchored weight. What

weight is required on the right to balance the 40 lb weight on the left?
According to your diagram, the answer is 20 lbs. Now do you see your
error?

--------------------top--------------
\anchor /anchor or pulley
\ /
\20 /20
\ /
\ /
\/
40
load with pulley
--------------------bottom----------

Not the same situation.

No. My first diagram is wrong in that the 20lbs should be 40. The
second is correct. Or am I misunderstanding your second part?

Permit me to clarify. I agree that your second diagram is correct. My point
is
that it's not the same situation as the first diagram, and thus the loads
in the second diagram *must* be different from the loads in the first. You
now
state correctly that the loads in the first diagram should be indicated as
40,
not 20, and I wish to emphasize that this is loadS plural, i.e. in both
segments of the rope -- thus the load on the top anchor in the first diagram
is in fact 80 pounds, not 40 as you stated in your text.

Nope. The load is still only 40. The second 40 is only the -same- 40
extended to another anchor.

No, it's not the "same" 40 pounds. It's an *equal* force, but separate.

Suppose that, instead of being tied to a cleat, the rope on the right side is
supporting a second 40-pound weight. You do see, I hope, that if the weight on
the right is not the same as the weight on the left, one or the other of them
will fall. For the system to remain in equilibrium, it is necessary that both
of the weights be the same -- that the downward forces on the ropes be equal.
Agree so far? ( I hope so. )

OK, so now we have a hook with a rope looped over it, and there's a 40-lb
weight at *each* end of the rope. How much weight is the hook supporting?
If you answered "40 lbs", go back and re-read this as often as necessary until
you realize that's wrong. If you answered "80 lbs" then continue.

Now disconnect the 40-lb weight on the right, and tie that rope off to a
stationary object. The weight on the left doesn't move, proving that the
system *remains* in equilibrium -- thus the force on the right side of the
rope is the same as it was before.

And therefore the force on the hook is the same as it was before, too: 80 lbs.

Yep, the weight with -two- 40lbs is 80 lbs on the hooks. Your mistake
is that there is only -one- 40 lb weight. Question. If you tie off
to the hook how much force is on the hook? To insist that there is 80
lbs when it is tied to the bottom cleat in the face of proof easily
availabe in books, on the net, even my explanations can be understood.
Refusal to due a simple 1 minute test to see if your adamant stance
is correct I -do not- understand. The only thing I can figure is you
are afraid of proving yourself wrong.

Harry K

Is isn't the things you know that will get you, it is what you know
that is wrong that will bite you in the ass.