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!

Box Pushed Up an Incline Ramp: Basic Newton's Law Questions

  1. Jul 22, 2015 #1
    1. The problem statement, all variables and given/known data
    A 90 kg box is pushed by a horizontal force F at constant speed up a ramp inclined at 28°, as shown. Determine the magnitude of the applied force.
    1. when the ramp is frictionless.
    2. when the coefficient of kinetic friction is 0.18
    2. Relevant equations
    μ= Fk/FN

    3. The attempt at a solution
    a) mg=(90)((.8)= 882N=Fg

    (0.469)(882)= Fgx
    414N=Fgx= magnitude of applied force

    b) FN=mg= 882N
    (882)(0.18)= Fk
    Fk= 158.76

    ** This is where I am unsure of my approach**

    Fapplied= Fgx+Fk
    =414N+158.76 N
    = 572N

    That seems like too much to me, but I'm not quite sure. Does it look like I have that equation correct ,or am I supposed to subtract the value I found for Fk from FgX, or something totally different. Any help would be very much appreciated
  2. jcsd
  3. Jul 22, 2015 #2
    You have not drawn FN correctly . Redraw correctly and try again .

    Hope this helps .
  4. Jul 22, 2015 #3
    oh okay, is it opposing the Fy aspect instead of Fg? I was confused when I was drawing that! Thank you for your response
  5. Jul 22, 2015 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Yes. The normal force opposes that component of gravity which would cause acceleration perpendicular to the surface ( the incline plane).
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Box Pushed Up an Incline Ramp: Basic Newton's Law Questions