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Homework Help: An ice cube goes up a ramp

  1. Dec 14, 2014 #1
    Question statement
    A 55g ice cube can slide without friction up and down a 25∘slope. The ice cube is pressed against a spring at the bottom of the slope, compressing the spring 10cm . The spring constant is 25N/m. When the ice cube is released, what distance will it travel up the slope before reversing direction?

    Relevant equations
    [itex]PE_s = PE_g[/itex]
    [itex]PE_s = 1/2kx^2[/itex]
    [itex]PE_g = mgh[/itex]

    Attempt at a solution
    Maximum height is when all energy is converted to gravitational potential energy (frictionless environment)


    [itex]PE_s = PE_g[/itex]

    [itex]1/2kx^2 = mgh[/itex]

    [itex]1/2(25N/m)(0.1m)^2 = (0.055kg)(9.8m/s^2)(h)[/itex]

    [itex]h = 0.23m[/itex] or [itex] 23 cm[/itex]
    (Answer is asked for in cm)

    Not sure what I am doing wrong here...
  2. jcsd
  3. Dec 14, 2014 #2


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    You computing the height, not the distance along the slope.
  4. Dec 14, 2014 #3
    I'm so silly. I need to learn to read questions further before answering something different.

    Distance up slope would be
    [itex]0.23(sin 35°) = 0.40m = 40cm[/itex]

    but thats not right!!!

    How do I compute the distance up the slope?
  5. Dec 14, 2014 #4


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    Wasn't it a 25º slope?
  6. Dec 15, 2014 #5
    Yes, it was... Thanks...

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