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Pythagorean Theorem and Pendulums

  1. Jun 7, 2007 #1
    1. The problem statement, all variables and given/known data
    Calculate the maximum speed of the 100 g pendulum mass when it has a length of 100 cm and an amplitude of 50cm. sorry my computer won't access the other thread. i don't know any other laws of conservations of energy or trig very well. also, when the pendulum as an amplitude of 50 cm , how does this lend me knowledge.

    2. Relevant equations
    pythagorean theorem (i would like to use this).
    a=9.8 m/s2
    what does amplitude mean, the pendulums height, or how far the pendulum is from its maximum speed point

    3. The attempt at a solution
    max of pendulum is at bottom.
    pendulum starts gainig speed of a from top till reaches bottom.
  2. jcsd
  3. Jun 8, 2007 #2

    Doc Al

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    Staff: Mentor

    I assume that this means the pendulum mass reaches a height of 50cm above the lowest point.

    Hint: Consider conservation of mechanical energy.
  4. Jun 8, 2007 #3
    you cannot solve this problem without using pythagorean theorem, so don't worry :smile:
    the amplitude of a pendulum is the displacement of the bob from the equilibrium position. it is not the arc length or anything, it is the displacement.

    first draw a figure and call one of the distances you don't know x
    then write the others in terms of x

    then, u will need to solve a quadratic which u will form by using pythagorean theorem. and u will get 2 values for x. which one do you think is more reasonable to use?

    when u get x, construct an equation concerning conservation of energy. think about what the maximum speed impilies

    then solve your equation to get the max. speed
  5. Jun 8, 2007 #4
    the amplitude of a pendulum is defined to be the displacement from the equilibrium position
  6. Jun 8, 2007 #5

    Doc Al

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    Staff: Mentor

    Good point! :wink:
  7. Jun 9, 2007 #6
    Soley101 did u get the answer?
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