Pulley Task

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Pulley Task

Post by Jim_R »

Discussion for Pulley task.
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Re: Pulley Task

Post by maggymay »

Gack, what the [blank inserted ok?] is an IMA 3 pulley? (off to go do some endless researching). Hey, if anyone could 'splain it here that would be wonderful :D .
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Re: Pulley Task

Post by penclspinner »

maggymay wrote:Gack, what the [blank inserted ok?] is an IMA 3 pulley? (off to go do some endless researching). Hey, if anyone could 'splain it here that would be wonderful :D .
Got to love wikipedia. Basically it's the mechanical advantage with regard to the ratio of distances between the effort (weight) and resistance (counterweight).
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Re: Pulley Task

Post by Dark Sabre »

Well, the IMA stands for Ideal Mechanical Advantage. They use this instead of the Actual Mechanical Advantage so that a judge doesn't have to put a force gauge on your system. With some understanding of pulley systems, the IMA can be determined just by inspection.

Wikipedia has a useful illustration of some possible setups:
http://upload.wikimedia.org/wikipedia/c ... ulleys.svg

Like on the first one, the Load is 100N and the Force applied is 100N (and the displacement of the load and force are also equal) so the IMA is 1
The second one, the Force applied is half of the Load (and the displacement of the force is twice that of the load) so the IMA is 2.
etc

There's a lot of ways to set up the pulleys to the same effect, so that #3 there is hardly your only option.

And pencl beats me, curses.
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Re: Pulley Task

Post by maggymay »

penclspinner wrote:
maggymay wrote:Gack, what the [blank inserted ok?] is an IMA 3 pulley? (off to go do some endless researching). Hey, if anyone could 'splain it here that would be wonderful :D .
Got to love wikipedia. Basically it's the mechanical advantage with regard to the ratio of distances between the effort (weight) and resistance (counterweight).
Just came back in to do some more research...lol pencl & DarkS, you say all that as if a noob will understand it :D . I'll have to see if I can find some pictures/images that make sense to me :) .
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Re: Pulley Task

Post by DeltaHat »

National Event Supervisor - Mission Possible
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Re: Pulley Task

Post by missionimpossible »

I saw the wikipedia pictures (#3), but are there any other ways to set up this pulley system?
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Re: Pulley Task

Post by illusionist »

Does the pulley system in this video:
http://www.youtube.com/watch?v=MZPvgdBIOhU
Count as an IMA 3 pulley system?
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Re: Pulley Task

Post by fleet130 »

Can't to tell from the video. A fixed pulley has an IMA of one. A movable pulley (entire pulley must change location, rotating the sheave in the pulley doesn't count) has an IMA of 2. All the pulleys appear to be fixed, so the IMA would still be 1.

Image
In the above example, there are 3 portions of the string that get shorter as the end of the string (with the arrow) is pulled. For every 3 inches of string that is pulled at the arrow, the weight is raised 1 inch. This makes the IMA = 3.
Information expressed here is solely the opinion of the author. Any similarity to that of the management or any official instrument is purely coincidental! Doing Science Olympiad since 1987!
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Re: Pulley Task

Post by illusionist »

fleet130 wrote:In the above example, there are 3 portions of the string that get shorter as the end of the string (with the arrow) is pulled. For every 3 inches of string that is pulled at the arrow, the weight is raised 1 inch. This makes the IMA = 3.
So the ratio of this pulley system is 3:1 right? In order to raise the mass 15cm, the string would have to be pulled at least 45cm?
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