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Homework Help: Can you help me please?

  1. Apr 13, 2008 #1
    Hello all,

    I have a little problem solving these 2 problems, guess you all can help me cuz its piece

    of cake for you all.

    Ok here we go:

    1. Old faithful geyser in yellowstone national park shoots water every hour to a height of

    40.0m. With what velocity does the water leave the ground?

    2. A pendulum with a mass of 1 kg is released from a height of 1.5cm above the height of

    its restin position. How fast will the pendulum be moving when it passes thorugh the

    lowest point of its swing?

    Dunno why when I saw this kind of problem(like number 1) ,only giving 1 value, is kinda

    to solve for me..

    Note: Sorry about my bad english :cool:
     
  2. jcsd
  3. Apr 13, 2008 #2

    Doc Al

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    Staff: Mentor

    To get detailed help, please show your work and point out where you got stuck.

    Hint: Both problems can be solved using conservation of energy.
     
  4. Apr 13, 2008 #3
    Errn.. Well, I cannot post any link cuz I dont have 15 posts nor image cuz it exceeds the

    required size.

    I can tell the answers, 1. Vf= 28m/s

    2. Vf=0.55m/s

    Thats what I have at the moment, is it correct?
     
  5. Apr 13, 2008 #4

    Doc Al

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    Staff: Mentor

    Show how you got those answers. (We don't need to see a diagram.)
     
  6. Apr 13, 2008 #5
    PE = KE

    vf^2= 2mgh/m=2gh

    Vf^2=2*40*9.81

    Vf^2=784.8

    Vf=28.0m/s

    ----------------

    PE = KE

    I changed 15cm into m so it will be = 0.15

    PE=mgh

    PE=1(9,81)(0.15)

    PE=1.5

    KE=1/2mgv^2

    KE= 1/2(1)

    KE= 0.5

    KE/PE= Vf^2

    0.5/1.5=Vf^2

    0.3=Vf^2(Apply square root to both side)

    0.55=Vf


    I got it this way.. tell me if Iam wrong
     
  7. Apr 13, 2008 #6

    Nabeshin

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    Science Advisor

    In the future, try to use a little more descriptive title. Perhaps something that actually pertains to the content of your inquiry.
     
  8. Apr 13, 2008 #7
    Ok I will
     
  9. Apr 14, 2008 #8

    Doc Al

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    Staff: Mentor

    Your solutions look good to me.
     
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