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: Stick slip friction, spring force.

  1. Mar 15, 2009 #1
    1. The problem statement, all variables and given/known data

    The block has mass m. A spring (with spring constant k and equilibrium length b) is
    attached to the block at the point x. The free end
    of the spring is at the point xb. We move the free end of the spring with a constant
    velocity u. The static and dynamic coefficients of friction for the contact between the
    block and the bottom surface are μs and μd respectively. The acceleration of gravity
    is g = 9.8m/s2.
    The block starts at the position x(t0) = 0 at the time t0 = 0. The position xb of the
    free end of the spring is xb(t0) = x(t0) + b at t0.

    If the block starts at rest, what is the extension [tex]\Delta[/tex]xc = ([tex]\Delta[/tex]xb − [tex]\Delta[/tex]x) of the spring when
    the block starts moving?
    Last edited: Mar 15, 2009
  2. jcsd
  3. Mar 15, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi MaxManus! :wink:

    (is the spring vertical? :confused:)

    Show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
  4. Mar 15, 2009 #3
    Thanks for answering
    No, the spring is horizontal.

    I must admit that I don't have anything to show I don't know how to attack the problem other than, which was given in the exercise.

    F = k(xb -x -b)i
    Last edited: Mar 15, 2009
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook