1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

2D Motion Finding the resultant using components

  1. Nov 27, 2011 #1
    1. The problem statement, all variables and given/known data

    A person walks 20m [N20(degrees)E], then 120m [N50(degrees)W], then 150m[W], and finally 30m [S75(degrees)E]. Find the person's final displacement.




    2. Relevant equations

    Is my solution correct? The textbook answers are 230m[N23(degrees)W]
    What did I do incorrect? Explain please :/ :(



    3. The attempt at a solution

    *Horizontal Component*
    (20m)cos70
    -(120m)cos40
    -150m
    (30m)cos75


    Total for horizontal component: -227m


    *Vertical Component*
    (20m)sin70
    (120m)sin40
    0
    -(30m)sin75

    Total for vertical component: 67m


    Total displacement = sqrt(-227m^2)+(67m^2)
    =237m

    Direction: tan^-1(67m/227m)
    =16.4


    Answer= 237m[W16(degrees)N]
     
  2. jcsd
  3. Nov 27, 2011 #2
    c'mon someone must be here

    D:
     
  4. Nov 27, 2011 #3
    When you say "[N20(degrees)E]" do you mean 20 degrees North of East?
     
  5. Nov 27, 2011 #4
    yes

    it basically says [N20E]

    Expect the 20 has a degree subscript. I suck with reading degree's
     
  6. Nov 27, 2011 #5
    It seems like you're first finding the compliment of the angle before you're breaking down the vector. If you do this, note that you're looking at the opposite angle and then the sine/cosine convention would change.

    EDIT:
    Try solving the problem by leaving the angles (instead of finding the compliment - which would just make things harder) they way they are and drawing out triangles to represent displacements in the x- and y-direction. Then, after you break down all of them, sum each x- and y- and take the vector sum.
     
    Last edited: Nov 27, 2011
  7. Nov 27, 2011 #6
    what do you mean?

    My solution looks right...
    I'm only off by 7m for the displacement but for the notation I got 16 degrees but it should be 23, idk how I'm off by that much.


    Did you do the solution? :s
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: 2D Motion Finding the resultant using components
  1. 2D Motion Find speed. (Replies: 1)

Loading...