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Homework Help: Girl Riding down hill (Friction)

  1. Nov 6, 2009 #1
    1. The problem statement, all variables and given/known data
    A girl coasts down a hill on a sled, reaching level ground at the bottom with a speed of 6.2 m/s. The coefficient of kinetic friction between the sled’s runners and the hard, icy snow is 0.059, and the girl and sled together weigh 736 N.The acceleration of gravity is 9.81 m/s2 .
    How far does the sled travel on the level ground before coming to a rest?

    2. Relevant equations
    Vf^2 = Vi^2 + 2ax

    Ffr (force friction) = Coefficient of friction * Fn (normal force)

    3. The attempt at a solution
    I'm thinking that I have to find the acceleration of the girl and the sled, but I don't think that I am given enough information necessary to solve for that. I just do not know how to approach the problem.
  2. jcsd
  3. Nov 7, 2009 #2
    What kind of forces are involved that affect her motion?

    What exactly you think you are not given?
  4. Nov 7, 2009 #3
    I think that I need the angle of the hill she is sliding down to find out the acceleration because I certainly think that she is sliding down the hill, and I know that friction affects her motion.
  5. Nov 8, 2009 #4
    I also know that there is acceleration involved at some point, but I don't know how long it took her to decelerate from 6.2 m/s to 0 m/s. I'm REALLY FRUSTRATED at this point because whenever I setup Force and Kinematic equations, I'm always missing TWO variables. I would like someone to HELP me. The problem, I think, fails to give me enough information.............

    Damion (sorry for the rant!)
  6. Nov 8, 2009 #5
    Fg acts down on the sled while Fn keeps the sled on the ground. Ffr acts to the right because I assume she is moving to the left. However, is the hill at an angle? I think it is, but if it is, I don't know how to find the angle. PLEASE, SOMEBODY HELP!!!
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