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!

Homework Help: Component method vector problem

  1. Sep 6, 2009 #1
    Use the component method to find the resultant(direction and magnitude) of the three forces shown.

    Could someone please verify my answers or tell me where I went wrong.

    Ax = 500 Cos 30 = -433N
    Ay = 500 Sin 30 = -250N
    Bx=-250 N
    By= 0
    Cx=200 Cos 20 = 187.9N
    Cy= 200 Sin 20 = 68.4N

    R = (-433-250+187.9)I + (-250 + 0 + 68.4)j
    = (-495.1, -181.6)
    R = sqrt(-495.1^2 + -181.6^2)
    = 527N

    Tan Theta = 318.4 / 370.9
    Theta = 20.1 deg.

    Attached Files:

  2. jcsd
  3. Sep 6, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Re: Vectors

    That seems right.

    Looks like the "318" and "370" are typos, and that you actually (and correctly) used 181.6/495.1 instead.

    You'll also need to specify which half-axis that angle is measured from (+x, +y, -x, or -y), and whether the angle is above/below/right/left of that half-axis.

    If you don't specify that, people normally assume it's from the +x axis, in the counterclockwise direction.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook