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!

Static Friction

  1. Mar 6, 2015 #1
    1. The problem statement, all variables and given/known data
    BaQTzvR.png

    2. Relevant equations
    Fs = μ FN

    3. The attempt at a solution
    Ok, so I drew a free body diagram and tilted it 90 degrees so that Fg of the small box points right and Fstatic points left.

    Fg = 4.7 kg x 9.8m/s2 = 46 N

    we want Fs to equal 46 N , correct? so we use the formula

    Fs = (0.71) x FN

    FN being the force of big box on small box

    .71 x FN = 46 N

    FN = 64.8N

    Which is wrong. any help?
     
  2. jcsd
  3. Mar 6, 2015 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    You calculated the normal force between the boxes, but you need the applied force, F.
     
  4. Mar 6, 2015 #3

    billy_joule

    User Avatar
    Science Advisor

    What is the required acceleration of box one? How is the mass of box one relevant?
     
  5. Mar 6, 2015 #4
    oh, silly me.

    so the acceleration of the small box should be 64.8 / 4.7k which is 13.8 m/s^2

    we use F=ma , m being mass of both boxes together and a being 13.8 m/s^2

    F = 465 N
     
  6. Mar 6, 2015 #5

    ehild

    User Avatar
    Homework Helper
    Gold Member

    Correct!
     
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: Static Friction
  1. Static friction (Replies: 12)

  2. Static friction (Replies: 6)

  3. Static friction? (Replies: 8)

Loading...