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Homework Help: Force required to pull a curtain out/in?

  1. Mar 14, 2016 #1
    • Member advised to use the homework template for posts in the homework sections of PF.
    Hi there, I am currently trying to work out what force I will need to pull the curtain out and in (in the system shown in the attached illustration) so that I can calculate the torque required to turn the black cylinder component and therefore find out what motor I will need.

    I am simply looking for a place to start or even a rough outline of how this can be calculated since at the moment I don't even know where to begin. It seems like there are forces all over the place in different dimensions and I am not sure how to simplify this for hand calculation.

    If a hand calculation will be too difficult, is there anyway I could set up a simple experiment to calculate it?

    Thanks for your time

    Attached Files:

  2. jcsd
  3. Mar 14, 2016 #2
    There are so many variables in how that system COULD be built that would affect the force required, and you have no dimension listed at all. IMO you would need to start with an experiment and - if you are looking to actually build something like this - probably plan on double the force for the prototype.

    Go to a store that sells blinds that are similar and measure the force needed on the cord to open / close the blinds. Tell them it is for a science project. You can probably do it with a fish scale.
  4. Mar 14, 2016 #3
    really good advice.
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