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Homework Help: Frictional Torque Question (Electrical Student)

  1. May 8, 2016 #1
    • Thread moved from the technical forums, so no HH Template is shown.
    Hey guys, thanks for taking a peek at my post! <3

    For a part of my Electrical Engineering course we are required to complete a Mechanical Science paper, for which we only had very few lessons. As it's not my area of expertise or focus, I'm flicking through what little notes I have and pretty much going insane! I've reached Task 3, and I've hit a wall.

    If anyone could give me a nudge in the right direction (or even spell it out for me!) I'd appreciate it.

    Ok so here's the question:


    I've tinkered with a few formulas but the only examples I have in my notes that are remotely similar to this task are too different from this one for me to be confident enough to apply my knowledge here.

    Thanks everyone, really appreciate it!
  2. jcsd
  3. May 8, 2016 #2


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    Science Advisor
    Gold Member

    (1) Draw a nice big clear diagram of what you think this mechanical system looks like . Mark in any forces that you think are acting . Post your diagram for us to look at .

    (2) Search on keywords : ' Polar moment of Inertia ' and ' Angular Acceleration '

    Come back with any questions .
  4. May 8, 2016 #3
    Thanks for replying, I'd already drawn this going by what notes I have, but I'm not sure what P, Ff, mg or ma are. Thanks

  5. May 8, 2016 #4


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    Staff: Mentor

    Hi HarleyQuinn. Welcome to Physics Forums.

    Things you'll need to research / become familiar with in order to address this problem:

    1. Newton's laws: F = ma in particular; How weight relates to mass.
    2. Rotational motion: Moment of inertia, torque, radius of gyration and how it relates to the mass and moment of inertia.
    3. The relationships between linear force and acceleration and torque and angular acceleration particularly when looking at forces applied to a rotating disk (drum or pulley).
  6. May 8, 2016 #5
    Thanks I'll take a look :)
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