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Homework Help: Vertical and horizontal components,physics As level help :(

  1. May 22, 2017 #1
    1. The problem statement, all variables and given/known data
    This is paper from june 2016 , the link below;
    http://qualifications.pearson.com/c...2013/Exam materials/WPH01_01_que_20160524.pdf
    Can someone pleeeeeze explain how to solve question 15 part B AND queation 16 part B .
    I have an exam tmrw so plz plz if someone could explain this to me :cry:

    2. Relevant equations
    How do write the answer in part b of Q16
    How to solve the question?

    3. The attempt at a solution
    for question 15 I tried using the tension formula T=mg+ma but dont know how to subtitue quantities in it
    for question 16 I dont understand what the question is asking about angles , all I could understand that forces cancel out now if its right or no idk but idk how to write the answer :(
  2. jcsd
  3. May 22, 2017 #2


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    Hi Maryam, :welcome:

    At the risk of being severely punished by our good mentors (answering is forbidden in PF, we are only allowed to help according to the rules ) - but heck, damsels in distress....

    For 15a you may assume the whole lot is just hanging: no acceleration. There's only one fundamental difference between the fly FBD and that for the spider: there is a T1 pulling down. Once you have the FBDs you also have the equations for equilibrium (= hanging still).
    Quantities are the givens (all in the form of symbols).

    But you appear to ask about 15b: They give T1 and you will need to solve TWO equations of the type T=mg+ma : one for the fly and one for the spider. Look at the FBDs and write them down (in terms of the symbols).

    For 16: You solved a) ? For b) you could look at T as a function of ##\theta## Or you could look at the horizontal component T##\sin\theta## because that is what is pulling the pole tips towards each other.
  4. May 22, 2017 #3
    Aww thanks !:-p
    What does FBD mean ?? And in question 15 they asked for the acceleration not tension , How do I get that?? :frown:
    And question 16 I was asking about part b , Idk how to write the answer cuz I dont understand it
  5. May 22, 2017 #4


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    Free body diagram

    T2 - mflyg = ma for the fly
    T1 - T2 - mspiderg = ma for the spider.

    a is the same for both (The distance between them does not change). Eliminate T2 and there you are !

    16: if ##\theta## increases, the horizontal components of T decrease, so the poles are not pulled together so hard any more. The vertical components remain the same.
  6. May 22, 2017 #5
    ooh! ok Thank u so much :) :dademyday:
  7. May 22, 2017 #6


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    You're welcome. Good luck with the test.
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