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!

A puck slides a total of 12m: Problem relating kinteic friction to Newton's law

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

    In a shuffleboard game, the puck slides a total of 12 m before coming to rest. If the coefficient of kinetic friction between the puck and board is 0.28, what was the initial speed of the puck?

    2. Relevant equations
    a=delta v/t

    3. The attempt at a solution

    I tried to find the acceleration using the equation above but since I don't know the initial speed, I get 2 unknown. I tried to substitute a by delat v/t but I don't have time either. I don't have the mass of the puck either so I can't find the normal force. How can I start?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Nov 1, 2009 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Use Newton's 2nd law to find the acceleration. (You don't need the actual mass--just call it m.)
  4. Nov 1, 2009 #3
    From Newton's law: you can find accleration of puck.
    P + Ff + N = ma

    After find a, you will use this eq:
    [tex]v^2 - v_0^2= 2as[/tex]

    Because puck is at rest after going distance = 12m, v = 0. Plug a, then you get answer.
  5. Nov 1, 2009 #4
    Thanks to both of you, I got it! I didn't see the masses canceled in the first equation.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook