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Homework Help: Acceleration (with and without friction)

  1. Mar 26, 2009 #1
    1. The problem statement, all variables and given/known data
    Consider the skier on the slope. She and her equipment have a mass of 60kg. She is on an incline that makes a 25deg incline [she is sliding down the hill].
    a. what is her acceleration if friction is negligible?
    b. what is her acceleration if friction is known to be 45N?

    2. Relevant equations
    Fnet = ma
    3. The attempt at a solution
    Fnet = ma
    588sin25 = 60a
    a = 1.30 m/s^2

    Fnet = ma
    588sin25 - 45 = 60a
    a = 2.05 m/s^2

    im not sure what im doing wrong. but the answer book says i should be getting a) 4.41m/s^2 and for b)3.4 m/s^2. If someone could please explain where im going wrong that would be greatly appreciated :)
  2. jcsd
  3. Mar 26, 2009 #2
    You seem to be setting up the problem correctly, but the calculation is off. Try instead to find the answer with acceleration isolated (a=F/m). That might make calculating things simpler.
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