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!

What is force if acceleration is .75? (inclined plane)

  1. Dec 10, 2011 #1
    1. The problem statement, all variables and given/known data
    A horizontal force F is exerted on a 20kg box to slide it up a 30 degree incline. The friction force retarding the motion is 80N. How large must F be if the acceleration of the moving box is to be .75 m/s^2?


    2. Relevant equations
    All the forces on the box in the x and y direction have to equal zero

    F=ma
    F-Ff-Fn = ma


    3. The attempt at a solution

    Using F-Ff-Fn,

    F-80-20*9.8*sin(30) = 20*.75
    F-178= 15
    F= 193 N

    Which isn't even close to what the answer is supposed to be, which is F=220 N
     
  2. jcsd
  3. Dec 10, 2011 #2

    gneill

    User Avatar

    Staff: Mentor

    If the box is accelerating then there must be a net force. Newton's first law.
     
  4. Dec 10, 2011 #3
    How does that change my equations?
     
  5. Dec 10, 2011 #4

    gneill

    User Avatar

    Staff: Mentor

    Draw a Free Body Diagram for the box. There must be a net force that produces an acceleration of 0.75m/s2 (acting up-slope). So what forces act along the slope?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: What is force if acceleration is .75? (inclined plane)
Loading...