"Stormin Mormon" wrote in message
...
Hey, mike, you're confusing the issue! If you have 500 pounds hanging on a
block and tackle, it doesn't matter how many ropes, the screwhook at top
is
still holding 500 pounds (and now I'm confusing the issue).

--


Stormy, you have proven again, without a doubt that you do not know what you
are talking about!
In a situation I described, the hook in the ceiling will feel 2 times the
weight of the flower pot. If you use a more complex block and tackle, one
with several pulleys top and bottem, the more wraps and pulleys you use the
lower the load on the hook in the ceiling, but it will never be less than
the weight of the flower pot, plus the weight of the block and tackle and
the force needed on the rope to suspend the object.

The only way to have less load on the hook than the object weighs is to use
a pulley and the flower pot, and two hooks on the ceiling. then each hook
will hold 1/2 the weight.

If anyone fails to understand this, do as another poster did and get a fish
scale, a pulley, a weight, and a pice of rope, and try it your self!

Think of ot this way, the pot weighs 40 lbs. If you had a pot hanging on a
length of rope hooked to the ceiling, the rope, hook and all feel a load of
40 lbs. If you add pulley at the ceiling and run the rope over it and back
down, you need to apply a force of 40 lbs to suspend the pot, any more or
less force applied and the pot will go up or down. Now you have TWO 40 lb
loads, the pot, and the force to ballance the weight of the pot, which will
be equal. In this case 40 lbs X 2 = 80 lbs.

Another way is to think of this whole rope and flower pot situation as a
tetter-totter. You have a 40 lb kid on one side, so you need a 40 lb kid on
the other side to balance it. The weight the fulcrum of the tetter-totter
feels is 80 lbs. Asssuming the tetter-totter weighs nothing.

One 40 lb kid is the flower pot, the other 40 lb kid is the force on other
end of the rope needed to suspend the pot, and the fulcrum is the pulley or
hook.

Tomorrow night we will discuss complex block and tackles, test at 10 PM!!
;-)
Greg