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Homework Help: Inclines with springs

  1. Oct 21, 2007 #1
    1. The problem statement, all variables and given/known data

    A spring with k = 40.0 N/m is at the base of a frictionless 30.0° inclined plane. A 0.50 kg object is pressed against the spring, compressing it 0.4 m from its equilibrium position. The object is then released. If the object is not attached to the spring, how far up the incline does it travel before coming to rest and then sliding back down? (See the figure below.)


    2. Relevant equations

    i have no idea :-(

    3. The attempt at a solution

    I can do a regular spring constant problem with out the incline. How do i do it with the incline when the height of the incline or the distance of the incline are not given?
  2. jcsd
  3. Oct 21, 2007 #2
    Since the floor is frictionless, it doesn't matter how far away the spring is. You don't need the distance of the incline or the height. (You can assume it's big enough so the block doesn't fall off or anything like that).

    All the spring does is give the block some initial velocity at the base of the incline. Remember the "good old days" when you just threw up a ball with some initial velocity and you had to figure out the maximum height? It's the same thing as soon as the block isn't in contact with the spring anymore. Once you find the height you can find the distance up the incline with trig.
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