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Homework Help: Dynamics Problem (suitcase pulled across floor find Fn)

  1. Mar 2, 2013 #1
    1. The problem statement, all variables and given/known data
    At the airport, you pull a 20 suitcase across the floor with a strap that is at an angle of 42° above the horizontal.Find the Normal Force.

    2. Relevant equations

    3. The attempt at a solution

    I have broken it down into all equations with just variables trying so solve for the normal force but i just can't seem to get it i don't know if i assume constant acceleration or not and if the Force applied Y is included in the normal force or if it is separate i am fairly certain it is separate but i could be wrong. Any help at all will be very appreciated. Thanks in advance.
  2. jcsd
  3. Mar 2, 2013 #2

    Doc Al

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    Staff: Mentor

    Looks to me like some information is missing in the problem statement. Have you posted the complete problem word for word as given?
  4. Mar 2, 2013 #3
    There is info given for part b but for this part (part a) my assignment expects me to complete it without any other info, but it seems to me that it can not be done, but often I know the imposible is possible in physics, hence why I came here :P
  5. Mar 2, 2013 #4

    Doc Al

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    Staff: Mentor

    Well, unless you are told the pulling force (or are given enough information to figure it out, which does not appear to be the case) there's not much you can do to find the normal force.

    What additional information is given for part b?
  6. Mar 2, 2013 #5


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    Gold Member

    .. such as, coefficient of kinetic friction, e.g.
  7. Mar 2, 2013 #6


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    hi chiuda! :smile:
    you should assume the acceleration is zero

    even so, you can't find the normal force without knowing µ :redface:
  8. Mar 2, 2013 #7
    Ya ot gives me coeff of kin friction and assume acceleration is zero in part be and qith that I know how to do it but I just wanted to see if you could do it without it for A because it wasnt given for that part
  9. Mar 2, 2013 #8
    ok i used the info from B and got it, thanks physics friends :)
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