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Homework Help: SHM/Spring Concept Questions

  1. Dec 12, 2009 #1
    Just going through some concept questions and these three have me stumped. If anyone can lend a hand.

    • If a uniform spring is cut in half, what is the force constant of each half? Justify your answer. How would the frequency of SHM using a half-spring difer from that using the same mass and the entire spring.
    • The analysis of SHM in this chapter ignored the mass of the spring. How does the spring's mass change the characteristics of motion?
    • Assuming a pendulum keeps perfect time at sea level, do you lose time, gain time or neither at a mountain top? (I want to say time runs slower from what I know of special relativity but what about just in classical physics?)
  2. jcsd
  3. Dec 12, 2009 #2


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    For the first question, ask yourself these question: What does the spring constant tell you? (I'm assuming that by "force constant" you mean what some textbooks refer to as the "spring constant".) Is it an intrinsic property of the metal out of which the spring is made? Does the length of the spring enter into its definition?

    For the second question, if you consider the mass of the spring in SHM does the total mass that is being accelerated going up or down? Where does mass enter into the parameters that characterize SHM, parameters like period, frequency, amplitude...

    For the third question, What equation tells you the period of a pendulum? Two values enter into this expression. One is gravity, the other is the length of the pendulum. Is gravity stronger at sea level or on a mountain top? Why?
  4. Dec 12, 2009 #3
    Thank you so much, this helped clear a lot of things up for me.
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