What is the mechanical advantage of this pulley system?

No homework...

Zero. None. Zilch. Nada. Atsá . Saa. Poi-e. Haan-haan. Namôya.

"The pulleys labeled with 'A' cannot move", therefore they will add sufficient braking action to the lash-up so that nothing will move.

Do your own homework.

I'm sorry I didn't formulate my question better. The pulleys labeled with 'A' are fixed at a point, for example the ceiling.

I also see that I've mixed up the numbers. This pulley system has a mechanical advantage of 3:1 * 4:1 = 12:1. Is this correct?

If I say 12:1 is the correct answer, and tomorrow your instructor asks you how you arrived at your answer, will you say, "I got it on CR4, from a total stranger, who is now my personal tutor"?

NOW: What is the mechanical advantage of this pulley system?

I'm sorry I did not formulate my answer better.

Do your own homework.

Okay, I'll explain how I got the mechanical advantage of 12:1.

The two rightermost pulleys have a mechanical advantage of 3:1. The other four pulleys have a mechanical advantage of 4:1 (we can use the line counting method here). I just want confirmation that this is a compound pulley system.

"I just want confirmation that this is a compound pulley system."

Yes! Yes! Yes, it IS a compound pulley system.

Finally. I'm glad that's over. I thought you wanted us to do your homework for you.

What a relief. For clarity: This pulley system has one stationary pulley and one fixed pulley. So, compound pulley system.

Finally, DO YOUR OWN HOMEWORK..

I am dis-owning you as a student.

Pulley - Wikipedia, the free encyclopedia

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Completely indeterminate, but certainly not 15:1 nor 12:1. The pulley on the right can go any old where compared to the others. The meaning of the red lines is not given, nor whether the leftmost rope end is fixed. What is the black line between the lower right pulleys?

The black lines are cords. The lower right pulley is connected to the main cord.

See the fourth system of this image:

The red lines are not cords, they just connect the pulleys. The two lowest pulleys move at the same speed.

7:1 (additive, not multiplicative).

SE and Lyn...you guys just got owned by Falcon. He completely blew off your "no homework" yammering and kept coming back with more. He then sucks Tornado into the fray and gets him to participate. This guy's a genius!!

<...This guy's a genius!!...>

That allegation is just so difficult to swallow.

What I meant was...he's a genius because he got you guys to participate regardless of your views on homework questions!...Geez, it's like having to explain a joke!

Anyway, it's irrelevant because he says it's not homework so...carry on.

Big deal. Such an ill-written homework question deserves to have cheaters.

7:1, but you need to explain that misterious line on the right side well. Otherwise, he will know, you cheated.

Let me get some things straight. First of all, this is not a homework question. I am just asking this out of curiosity. The image is also made by myself.

The rightmost moving pulley is connected to the main cord with a Prussik knot. We now basically have a Z-rig, with the third pulley labeled with 'A'. These two pulleys have a mechanical advantage of 3:1. The rightmost moving pulley is not directly connected to the load; it is connected to the main cord.

The other four pulleys form a 4:1 system. The moving pulleys are directly connected to the load.

So we have a 3:1 pulley system pulling a 4:1 system. Since the rightmost moving pulley is not directly connected to the load, and moves at a different speed that the other moving pulleys, we have to mulitply the mechanical advantage. This system will have a mechanical advantage of 12:1.

I don't have a book where the theory of this kind of pulley systems is explained. I got the theory from this video: http://youtu.be/O150ASX3Z8g?t=5m29s

The man has constructed a pulley system where a 3:1 Z-rig pulls a 3:1 pulley system, hence giving it a total mechanical advantage of 9:1. I've drawn a pulley system where a 3:1 Z-rig pulls a 4:1 pulley system. According to the theory in the video, the total mechanical advantage is 12:1, and not 7:1.

The reason I'm asking this question here is that I want to know if this theory is correct. I am not cheating, this is not a homework assignment and I don't have an instructor.

If this theory isn't correct, are there other ways to multiply the mechanical advantage with pulleys?

I'm thanking you in advance.

They things are tied together here, with several weights/pulleys moving in unison, the configuration is essentially parallel rather than series. That's why it adds rather than multiplies.

looks more like a wiring diagram of the starter circuit of a Cavalier , I could be wrong

Good grief...