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Pulling canvas/weight on slope

  1. Sep 12, 2005 #1
    *Edit Note: I apologize if this belongs in the homework or classic physics sections; I have been in a real hurry to post it, and I just assumed problem which is meant for real life application would not belong in a place for schoolwork, so I put it in the general board without anything more than a glance elsewhere. It was wrong not to read the sticky posts or think about other topics before putting this on the board, and I would move it myself if I could. Forgive me, I'm running on 5 hours of sleep and will be back to work in 5 more.*

    I am trying to figure out how much weight it will take to pull a canvas across a floor with a wieight hung on a pulley hung on a slope. I attach the canvas to a large metal pipe and use that to roll it up(using a motor and pulley system). The problem is I have to pull the canvas back into place, which is more work than necessary. Thus, I have devised a way to keep myself from having to do this. I suggest you take a good look at the attachment before/while I describe this...

    Firstly, to keep things simple, let us a assume a frictionless environment. Those are adjustments that can be made later. The floor the canvas is layed upon is 32 feet long. There is a room underneath 16 feet tall. Both of these are represented in black in the diagram. The canvas (blue), which weighs 50 lbs, is wrapped around a small pipe (brown) on the opposite end of the large roller. Attached to this pipe is a metal cord (red). The weight of the cord, I believe, is negligable (correct me if I'm wrong. In case I am, it will weigh less than or equal to 10 lbs, for our purposes). The cord goes over 2 pulleys (yellow) and is attached to a weight (cyan). Because I need to pull the canvas more than 16 feet, I need to hang the bucket from a seperate cord (green) with a wheel (also yellow) of sorts. The seperate cord is attached to each side of the room below the floor, and I figure I will want it at about a 30 degree angle. It would follow, then, that the weight will travel on a 30 degree slope.

    I would like to know how much weight I need to hang from the (green)cord in order to get the desired result of pulling the canvas all the way across the 32 foot floor. For my purposes, it would be more useful to know the logic behind the solution than the solution itself; I may need to make an adjustment to the angle of the cords. Please reply ASAP, and thank you in advance for any help you can give.

    Attached Files:

    Last edited: Sep 12, 2005
  2. jcsd
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