In article , wrote:
On 14 Mar 2004 10:24:11 -0800, (Harry K)
wrote:

| (Harry K) wrote in message
. com...
| "Greg O" wrote in message
...
| Harry,
| Is this drawing, really any differant from
|
| 20 20
| \ /
| \ /
| \ /
| \ /
| \ /
| 40
|
| this one?
|
|
| 40
| / \
| / \
| / \
| / \
| / \
| / \
| 20 20
|
| Greg
|
| No they are not the same: If the load in No.1 is 40 the drawing is
| correct. If the load in No.2 is 20 the drawing is incorrect. In no.2
| with load 20 the pull on the top will be 20 not 40.
| See my experiment that I used to confirm the theory. It confirms what
| I just said.
|
| Harry K
|
|
| A better explanation.
|
| Diagram 2 is a class 1 pulley. It only changes the direction of pull
| and does nothing to change the strain. If you were to tie off the
| left line at the top (hook) what will the strain on the hook be?
| Answer: 20 lbs, not 40. The 20lbs you are showing on the right leg is
| only the same 20 lbs extended to a different anchor, not an additonal
| 20 lbs.
|
| Diagram 1 is a class 2 pulley. It halves the load between two lines
| but requires, say, 10ft of rope pull to lift the load 5 ft.
|
| Harry K

Harry, you are absolutely and irrefutably correct. It's the difference
between two types of pulleys, one a simple pulley (the one fastened to
the ceiling) and one a moveable pulley (fastened to the weight, with
the rope tied to the ceiling on one side). It makes all the
difference.

*IF* we were discussing moveable pulleys, yes -- but we're not, and that
appears to be the source of confusion for both of you. Go back to the original
post in this thread, and find out what the discussion is all about. Then read
some of the followups, particularly those from Michael Daly, to find out
exactly why Harry is absolutely and irrefutably INcorrect.

By the way, these are principles known for thousands of years. The
pyramids were built using these simple machines and others. Leonardo
da Vinci commented on these pulleys. It's not opinion. There's nothing
to argue about. You don't even have to prove it with geometry -- as
Yogi Bera once said, "you could look it up."

Yes, you could. You could start by looking up the initial post in this thread.