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: Incline-Friction problem

  1. Sep 22, 2009 #1
    1. The problem statement, all variables and given/known data
    A 4 kg block is given an initial velocity of 5 m/s upward along a 30 degree incline. If the coefficient of sliding friction between the block and the surface of the incline is .42, find the upward displacement of the block along the incline, between the point of its initial velocity and the point at which it comes momentarily to rest

    2. Relevant equations
    Fg = ma
    Ffr = coefficient x Fg x cos theta
    V squared = V0 Squared + 2A(X-X0)

    3. The attempt at a solution
    Set it so Fg = 9.8 x 4
    Plug into Ffr equation
    Ffr = .42 x 39.2 x cos 30
    Ffr = 14.26
    Need help from here on
  2. jcsd
  3. Sep 22, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi TWPC920! Welcome to PF! :smile:
    ok, you've got the friction force, now use good ol' Newton's second law in the direction of the slope …

    Fslope = maslope, where Fslope is the sum of the friction force and the slope component of the gravitational force.

    Then use that value of aslope in the constant acceleration equation you mentioned. :smile:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook