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Homework Help: Understanding vectors, direction, and magnitude

  1. Sep 13, 2011 #1
    Hi, I need some help

    1. The problem statement, all variables and given/known data

    Three kids are pulling on a poor teddy bear. Andy is pulling with a force of 10N in the North direction. Ben is pulling with %N straight South, and Charlie is pulling with 8N in the West direction
    a) which direction will they move
    b) In what direction with what force should david pull to make sure the teddy bear doesn't move?
    2. Relevant equations


    3. The attempt at a solution
    Rx= 8N+0N, Ry= 10N + 5N
    North west direction?

    Please :)
  2. jcsd
  3. Sep 13, 2011 #2


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    Step 1: Draw a picture of what is going on, before David arrives on the scene.
    Step 2: Using this picture, what are the sum of forces applied to the bear in the x direction? The y direction?

    Additional steps to be supplied when you get step 2 correct. :smile:
  4. Sep 13, 2011 #3


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    Welcome to Physics Forums.
    I don't think "north west" is specific enough, they probably want to know how many degrees from north it will move.

    When you calculate Rx and Ry, you need to keep track of whether each force is treated as positive or negative. Usually north or east are positive, while south or west would be negative.
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