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Dynamics Quiz: Newton's Laws

  1. Nov 28, 2006 #1
    "John" the stair-slider was recently photographed sliding down a staircase. He has a mass of 98.0 kg when sitting on a carpet lubed up on the bottom with a kg of butter. The staircase is 8.2 meters long and makes an angle of 43 degrees with the horizontal. The butter reduces his frictional force to 50.0 N. Stavro begins his slide by running, grabbing his carpet, and launching himself on the stairs with a velocity of 4.89 m/s. Determine:

    A) John's acceleration (Draw a Force Diagram of the system to help you)
    B) How long is takes John to reach the bottom of the stairs
    C) John's velocity at the bottom of the stairs

    HELP ME PLEASE! i dont really know where to start
  2. jcsd
  3. Nov 28, 2006 #2
    Please show some kind of mental effort in working through the problem. What parts make sense, what equations are you working with... Nothing in your text gives you clues?
  4. Nov 28, 2006 #3
    A) Newtons law states that F = MA. Force = mass * acceleration. Since mass is constant throughout, as acceleration increases, what happens to the force?
  5. Nov 28, 2006 #4
    Also, is this really "advanced physics"?
  6. Nov 29, 2006 #5


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    Easy! Since it was Stavro who slid down the stairs, John will have no acceleration, will never reach the bottom of the stairs and will have no velocity at the bottom of the stairs!
  7. Nov 29, 2006 #6
    Stavro? i dont understand
  8. Nov 29, 2006 #7
    Stavro is the guy in the problem.
  9. Nov 29, 2006 #8
    ok i see, well if someone could just get me started with the problem it would be great
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