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: Forces diagram question

  1. Mar 4, 2006 #1
    with reference to the diagram, at what angle must the 800N force be applied in order that the resultant R of the two forces has a magnitude of 2000N.

    We were instructed to use the i,j method.

    So, the forces for Fi = 800sin(-) and Fj = 1400 + 800 cos(-) and the resultant is 2000N.

    This is where i get stuck, a^2 + b^2 = c^2
    so 2000^2 = (800 sin(-))^2 + (1400+800 cos(-))^2

    any help would be great.
     

    Attached Files:

    • pic.jpg
      pic.jpg
      File size:
      6.5 KB
      Views:
      139
  2. jcsd
  3. Mar 5, 2006 #2
    bump^

    please help :p
     
  4. Mar 5, 2006 #3

    Hootenanny

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    We can't see the attachment yet...
     
  5. Mar 5, 2006 #4
    it is simply a diagram showing

    |........./
    |......./
    |(-)./
    |.../
    |./

    with the verticle line saying 1400N and the diagonal line saying 800N
     
  6. Mar 6, 2006 #5

    mukundpa

    User Avatar
    Homework Helper

    It appears correct, expand

    2000^2= 800^2 sin^2(@) + 1400^2 +2*1400*800*cos@ + 800^2*cos^2@

    2000^2 - 800^2 - 1400^2 = 2*1400*800*cos@

    solve for cos@


    MP
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook