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!

May you please help me with grade twelve physics?

  1. Nov 22, 2008 #1
    Questions is...
    a small is resting on a larger box, which is resting on a table. When an applied force is applied to the larger box, the two boxes move together. The small box does not slip.

    If the acceleration of the pair of boxed has a magnitude of 2/5m/s^2, determine the smallest coefficient of friction between the boxes that will percent slippage.

    I'm not sure where to even start... If the object is accelerating, wouldn't the small box slip off eventually? Or are we supposed to find static friction? ....
     
  2. jcsd
  3. Nov 22, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    The only force accelerating the small box is static friction. What friction force is required? (Hint: Let "m" stand for the mass of the small box.)
     
  4. Nov 22, 2008 #3
    Thanks for replying!

    Would I need to use a formula where the masses cancel? The only value the question gives us is the acceleration... which is 2.5m/s². Also the 9.8N/kg which is always assumed...

    ...I'm looking for µ, right?
     
  5. Nov 23, 2008 #4

    Doc Al

    User Avatar

    Staff: Mentor

    The mass will cancel, which is why I suggest labeling it "m" and continuing.

    That's right.

    Hints: You'll need to combine two formulas: (1) Newton's 2nd law; (2) The formula for maximum static friction. (That second formula contains µ.)
     
  6. Nov 23, 2008 #5
    alright,
    so
    F(s) = ma

    F(N) - F(g) = 0
    F(N) = F(g)
    F(N) = mg

    F(s) = µ(s) F(N)
    ma = µ(s)mg
    a/g = µ(s)
    [2.5m/s²] / [9.8m/s²]= µ(s)
    therefore, the smallest coefficient of friction between the boxes that will prevent slippage is 2.6x10^(-1)

    something like that?
     
  7. Nov 23, 2008 #6

    Doc Al

    User Avatar

    Staff: Mentor

    Exactly like that. :approve:
     
  8. Nov 23, 2008 #7
    wow thanks
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: May you please help me with grade twelve physics?
Loading...