1. Not finding help here? Sign up for a free 30min 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!

Finding the Force

  1. Sep 18, 2009 #1
    1. The problem statement, all variables and given/known data

    Two forces F1 and F2 are acting on a mass M=4kg. The force F1 = 11i + 5j + 7k, in N. The acceleration of the mass is given by a = 3i + 7j + 4k, in m/s2. Calculate the magnitude of F2 .

    2. Relevant equations
    F = ma


    3. The attempt at a solution
    Ok so what I tried here is doing F1 + F2 = ma
    so F2 = (ma)- F1

    I took a = 3i + 7j + 4k and multiplied all of the components by 4kg got 44i+20j+28k and then subtracted F1 = 11i + 5j + 7k and got 41i+13j+24k kg*m/s^2

    what do I do?
     
  2. jcsd
  3. Sep 18, 2009 #2

    rock.freak667

    User Avatar
    Homework Helper

    ma=4(3i+7j+4k)=12i+28j+16k


    now subtract this from F1
     
  4. Sep 18, 2009 #3
    so i+23j+3k ? what units do I use for this? its saying im not using the right units. Isn't it N*m/s^2
     
  5. Sep 18, 2009 #4

    rock.freak667

    User Avatar
    Homework Helper

    'ma' is in N

    F1 is in N


    so if F2= ma - F1, then F2 is in N as well.
     
  6. Sep 18, 2009 #5
    cool I got it right it was 1i+23j+9k square the coeficents add them up and then square root to find the force N.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Finding the Force
  1. Find A Force (Replies: 10)

  2. Finding force (Replies: 4)

  3. Finding the Force (Replies: 44)

  4. Finding the Force (Replies: 5)

Loading...