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Homework Help: Sled placed at an inclined plane ( Newtons law)

  1. Jan 12, 2010 #1
    1. The problem statement, all variables and given/known data

    * This is for my project.
    The sled is placed at an inclined surface at an angle of theta. The sled is attatched to a rope, which i will be pulling to find out the minimum force to start the sled moving.
    i would assume that when im tryin to find the jusssttt jussst that point when it starts to move will i make Fnet = 0 ?

    im finding out different amount of tensions needed to pull the skier up depending on the angles. i will be increasing the the angle by 15 degrees every interval. starting from 30 degrees.

    --Im open to hear any opinions regarding my project, if you know that there is a way i could make it little bit more complex and interesting ? i will be very glad to hear them--

    2. Relevant equations

    Fnet = ma

    3. The attempt at a solution

    I know that when a mass of object is placed at an angle there is a
    friction force, x-component of the gravity. These two forces appose the Tension force.

    Ftension - Ffriction - Fgravityx = m a

    would acceleration be 0 in this case?

    so it would be Ftension = Ffriction +Fgravityx
    but if it wants to move Ftension > Ffriction + Fgravityx right??
    please HELP !
  2. jcsd
  3. Jan 12, 2010 #2


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    Homework Helper

    Acceleration would be 0 at the moment before the sled starts moving. Once it starts moving, acceleration is no longer 0 and the force of friction decreases significantly because it will then be kinetic friction, not static friction.
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