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Can someone check if this forces problem on an incline

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  1. Apr 4, 2016 #1
    To me the force P that pulls the bottom block up the incline seems a little low. Can someone confirm with my setup and work in brown is correct? Thank you.

    Problem:
    8eea061f2a.jpg

    Work:
    4c89ea0207.png
     
  2. jcsd
  3. Apr 4, 2016 #2

    BvU

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    Would you expect P to be independent of ##\theta## ?
    Draw a free body diagram for each of the blocks separately.
    And I see one of the two blue arrows (the most illegible one :smile:) can't be right.
     
  4. Apr 4, 2016 #3
    ΣFxA : P - T - (3mgsinθ) - μk mgcosθ= 0

    That was your hint right XD.
     
  5. Apr 4, 2016 #4

    SammyS

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    How about clearly stating what forces act on the plank and what forces act on the block - separately.

    The mass of the block is 2m, right. Why do you have 3m ?

    The plank acts on the block via friction and via the tension in the cord.
     
  6. Apr 4, 2016 #5
    4
    I will redo the problem and post it back up. Thanks for you input.
     
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