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Homework Help: Question About Pendulum

  1. Apr 12, 2013 #1
    1. The problem statement, all variables and given/known data
    Hi, I have a question about pendelum which I don't know how to solve

    A 1.0 kg ball swings from a pendulum and bounces into a spring with a spring constant of 750 N/m.

    Here is the diagram:
    Untitled.png

    1. How do i determine velocity of the ball at the bottom of the swing?
    2. How do i determine the maximum compression of the spring?

    2. Relevant equations



    3. The attempt at a solution
    Attempt for number 1

    h = 1.5 m - (1.5 m cos 15)
    h = 0.05111126 m

    Eg = Ek
    mgh = 1/2 mv^2
    gh = 1/2 mv^2
    2gh = v^2
    sqrt(2gh) = v

    v = 1.00 m/s
    Is that right?

    2. I don't know how to do 2.

    Thanks
     
    Last edited: Apr 12, 2013
  2. jcsd
  3. Apr 12, 2013 #2

    haruspex

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    That's a remarkable leap. What do you think h equals?
    For part 2, use energy again. How fast will the ball be moving when the spring is at maximum compression?
     
  4. Apr 12, 2013 #3
    For number 1:
    sqrt(2gh) = v
    sqrt(2(9.81)(1.5 - 1.5 cos 15))
    v = 1.0 m/s

    For number 2:
    1/2 mv^2 = 1/2 ke^2
    mv^2 = ke^2
    e^2 = mv^2 / k
    e^2 = (1.0 kg)(1 m/s)^2 / 750 N/m
    e^2 = 1/750
    e = sqrt(1/750)
    e = 0.036 m

    is this right?
     
  5. Apr 12, 2013 #4

    haruspex

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    Looks good.
     
  6. Apr 12, 2013 #5
    For both of them?

    If yes, Thank You for verification!
     
  7. Apr 12, 2013 #6

    haruspex

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    Yes, both.
     
  8. Apr 12, 2013 #7
    Appreciate your help!
     
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