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: Find the component of the Force along AC

  1. Dec 18, 2012 #1
    1. The problem statement, all variables and given/known data
    The 350-lb force is to be broken into components along the
    lines AB and AC.
    2. The component along AC is most nearly
    1. 175.0 lb
    2. 186.2 lb
    3. 202 lb
    4. 225 lb
    5. 239 lb
    6. 268 lb
    7. 294 lb
    8. 303 lb
    9. 404 lb
    10. 457 lb

    I have attached an image of the question

    2. Relevant equations

    3. The attempt at a solution

    I had thought that I could do 350cos(30) = 303.1
    But this answer is wrong. The answer is supposed to be 239 lb but I don't understand how to get it.

    Help would be appreciated.

    Attached Files:

  2. jcsd
  3. Dec 18, 2012 #2


    User Avatar

    Staff: Mentor

    Suppose instead that there was a mass producing the same force but suspended by two cables with the same geometry (but inverted, of course). How would you approach the problem of finding the tensions?
  4. Dec 18, 2012 #3
    Now I get it. Redrawing the picture as you suggested helped me recognize that I'd dealt with this before.

    0 = -350 + ACsin(60) + ABsin(50)

    0= AC cos(60) - ABcos(50)

    Rearranging this we get:

    AB= ACcos(60)/cos(50)

    Then I can plug this into the ƩFy thus allowing me to solve for Ac which is 239 lb.

    Thanks for your help. That change in perspective really opened the question up.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook