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: Magnitude of force acting on an object

  1. Oct 24, 2009 #1
    1. The problem statement, all variables and given/known data

    A 1.84kg mass is observed to accelerate at 10.66m/s^2 in a direction 28.8 degrees north of east. There is a force directed north acting on the object and a force directed east acting on the object. What is the magnitude of the force acting east on the object?

    2. Relevant equations

    F=ma, Fx=ma, Fy=ma

    3. The attempt at a solution

    *FA=force directed north, FB=force directed east, FN=normal force



    If I put the two equations together to cancel out FA, I still have two unknowns. I don't know what I'm doing wrong. Maybe my FBD was wrong?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Oct 24, 2009 #2


    User Avatar
    Gold Member

    Re: Forces/Acceleration

    Does this problem explicitly say gravity is even involved? This sounds like a simple vector problem.
  4. Oct 25, 2009 #3
    Re: Forces/Acceleration

    You're right. I didn't need to use forces to solve this:

    F = m*a
    = 1.84*10.66
    = 19.6 N

    If I draw a line from the origin 28.8deg north of east and derive the components, then Fx=the force eastward:

    Fx = 19.6 *cos(28.8) = 17.2 N
  5. Oct 25, 2009 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Re: Forces/Acceleration

    Looks good :smile:

    p.s. Welcome to Physics Forums.
  6. Oct 26, 2009 #5
    Re: Forces/Acceleration

    Thank you. I know that I'll be using this forum a lot more :approve:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook