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Simple harmonic motion of some mass

  1. Nov 15, 2011 #1
    1. The problem statement, all variables and given/known data
    A 0.25-kg mass is attached to the end of a spring that is attached horizontally to
    a wall. When the mass is displaced 8.5 cm and then released, it undergoes SHM.
    The force constant of the spring is 1.4 3 102 N/m. The amplitude remains
    (a) How far does the mass move in the first five cycles?

    2. Relevant equations

    3. The attempt at a solution
    not sure what the question mean the first 5 cycles is that the rpm?
  2. jcsd
  3. Nov 15, 2011 #2


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    Staff: Mentor

    Yeah, that makes no sense without a diagram. Is there a frictionless plane under the mass supporting it so all of its motion is horizontal? Or is it free to swing down and hit the wall or something?
  4. Nov 15, 2011 #3
    which the spring is attached to the wall horizontally meaning the object will move in the x-axis
  5. Nov 15, 2011 #4


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    Staff: Mentor

    One cycle is complete when a system returns to the same state that marked the beginning of the cycle. In the case of a mass-spring system (without friction), if the mass is in some given location with some given velocity, the cycle is complete when it again has that position and velocity. So if you start counting a cycle with the mass displaced by +8.5cm and zero velocity then one cycle is complete when the mass returns to +8.5cm and has zero velocity.

    When friction is involved you have to be a bit more careful in defining a cycle because amplitude will diminish during each one as energy is lost. It's often easier to measure a cycle from peak displacement to (same sign) peak displacement, or by successive crossings of the equilibrium point in the same direction.
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