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Hockey question please help thanks

  1. Dec 30, 2012 #1
    A hockey player sends a .4kg puck at 80 m/s. A stationary golie cathces the puck. If the coefficient of friction of the golie on the ice is .05 and his mass is 90 kg how far does he slide on the ice before he comes to a stop.

    I have found
    normal force = mg
    = 885.92N
    and then friction = .05(885.92N)
    = 44.296N
    and using conservation of momentum i found the velocity after the collision will be 0.35m/s
    but now im stuck
    please help.
     
  2. jcsd
  3. Dec 30, 2012 #2

    tiny-tim

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    Welcome to PF!

    Hi Loading! Welcome to PF! :smile:
    find the acceleration (btw, you didn't need to find the actual force :wink:) …

    then, since you know the initial and final velocities, you can use one of the standard constant acceleration equations to find the distance :smile:
     
  4. Dec 30, 2012 #3
    okay so this is what i have upto now:
    mass of puck = .4kg
    Speed of puck = 80m/s
    Mass of goalie= 90kg and he is at rest
    μ = 0.05

    i found the common velocity after the colision to be 0.35 m/s
    due to vertical equilibrium i stated that Fg=Fn
    Fn=mg
    Fn=885.92N
    and then Friction = μ x Fn
    Friction = 44.296N

    but i cant seem to find the acceleration. do i use the friction equation to find it...that will just give me 9.8m/s2
     
  5. Dec 30, 2012 #4

    tiny-tim

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    Hi Loading! :smile:
    uhh? :confused:

    just do what good ol' newton would have done …

    divide the force by the mass! :biggrin:
     
  6. Dec 30, 2012 #5
    ooh :D thanks dude
     
  7. Dec 30, 2012 #6

    tiny-tim

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    you have probably noticed that the acceleration is -µg …

    can you prove this? :smile:

    (you need to: it will save you time in the exam :wink:)
     
  8. Dec 30, 2012 #7

    TSny

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    tiny-tim, you need to upgrade your avatar.
     

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