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Homework Help: Potential Elastic Energy

  1. Nov 5, 2005 #1
    Can anyone help me with this question?

    A 0.240 kg block on a vertical spring with a spring constant of 5e3 N/m is pushed downward, compressing the spring 0.080 m. When released, the block leaves the spring and travels upward vertically. How high does it rise above the point of release?

    I know that PE= 1/2 kx^2
    so I got .5 x 5e3 x .08^2=16 I'm not sure where the mass comes into this equation. I also know that you have to subtract your anser from the point of release so i tried 16-.08 but it didn't work...

  2. jcsd
  3. Nov 5, 2005 #2
    Is the answer you got (16) a height? What units does it have? What units should it have?

    Secondly, if it reaches a maximum height while initially traveling upwards, then something must be pulling it down... what is it? (kinda obvious).
  4. Nov 6, 2005 #3
    16 joules is the potential energy
    where would you incorporate gravity or weight into the equation??
  5. Nov 6, 2005 #4

    Doc Al

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    Staff: Mentor

    Think of this as a conservation of energy problem. Intially, you have spring potential energy, which ends up being transformed into gravitational potential energy. How do you express gravitational PE as a function of height?
  6. Nov 6, 2005 #5


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    doesn't the block have P.E. as it travels upto to its max height; how would you define the P.E of an object at a certain height?
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