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!

Determining Coefficient of Kinetic Friction w/m, t, and v

  1. Mar 21, 2015 #1
    1. The problem statement, all variables and given/known data
    A 2.0 kg block of wood slides over a horizontal surface and comes to rest in 2.5 s. If its initial velocity was 9.0 m/s, what is the coefficient of kinetic friction?

    2. Relevant equations
    rho=mv
    change in rho=F*change in t
    Force of friction = mu*Force normal
    Force normal=mg

    3. The attempt at a solution
    rho=(2.0 kg)(9.0 m/s)=18 kg*m/s
    18 kg*m/s=Force of friction(2.5 s)
    Force of friction=7.2
    mu*Force normal=7.2
    mu(2.0 kg)(9.80 m/s squared)=7.2
    mu=0.37

    I don't know what the correct answer to this question is and I potentially may not know until the day of my exam. Can anyone tell me if I'm doing this correctly or if I'm missing something? I really appreciated it!
     
  2. jcsd
  3. Mar 21, 2015 #2

    berkeman

    User Avatar

    Staff: Mentor

    Looks good to me.

    F = ma = μN = μmg

    a = μg

    μ = a/g = [(9m/s)/(2.5s)]/(9.8m/s^2) = 0.367

    :smile:
     
  4. Mar 26, 2015 #3
    Thanks!
     
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: Determining Coefficient of Kinetic Friction w/m, t, and v
Loading...