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-   -   Net Forces (https://www.askmehelpdesk.com/showthread.php?t=770872)

  • Oct 11, 2013, 04:04 PM
    HSPhysics1001
    Net Forces
    What is the net force (or single equivalent force) of the following three forces

    F1- 50N East, F2-30 N NE and F3 60N W40degreesN.
    (Answer as a size and direction)
  • Oct 14, 2013, 07:12 AM
    ebaines
    When adding forces you start by breaking each force into orthogonal consituent parts - i.e a force component acting north + force component acting east. Then you add all the north comnponents of the three forces to get a total north componenet, and do the same for the east components of all three forces. Finally combine these totals into a single force with magnitude and direction. Post back with your attempt and we'll be happy to check it for you.
  • Oct 14, 2013, 10:57 AM
    HSPhysics1001
    How do I deal with F2 and F3? Im not sure what to do because one is going NE and the other is going a 40 degree angle.

    My attempt:

    F1-50N East

    F2-
    I decided to solve by finding the x and y components and because its at going NE used 45 degrees as the angle.

    Y-comp. 30Sin(45)=21.2N
    X-comp. 30Cos(45)=21.2N

    F3-
    Y-comp 60Sin(40)=38.6
    X-comp 60Cos(40=46N-Which is negative because its going West

    Anding them together
    X-Comp- 50N+21.2N+-46N=25.2N to the East
    Y-Comp-21.2N+38.6N=59.8N North
  • Oct 14, 2013, 11:04 AM
    ebaines
    Looking good so far. Last step is to combine the horizontal and vertical components of force. The magnitude of the resutant force vector comes from Pythagorus:



    and the angle can be found from



    Be careful when doing the arctangent calculation to be sure which quadrant should be in.
  • Oct 14, 2013, 03:44 PM
    HSPhysics1001
    Awesome thanks!

    64.8N and 67.1
  • Oct 15, 2013, 05:24 AM
    ebaines
    Quote:

    Originally Posted by HSPhysics1001 View Post
    Awesome thanks!

    64.8N and 67.1

    Be careful to define how the angle you got of 67.1 degrees is measured. Is it a bearing from north? Or degrees north of east?

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