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-   -   Oscillations (https://www.askmehelpdesk.com/showthread.php?t=524749)

  • Nov 10, 2010, 04:20 PM
    heyyalliee
    Oscillations
    The position of a mass oscillating on a spring is given by x = ( 3.2cm)Cos[2(pi)(t)/ .74seconds]
    What is the first time the mass is at the position x = 0?

    I was able to calculate the period of motion which is .74 seconds.

    I am having the hardest time figuring out the time when the position is 0. Maybe its my algebra?


    Thanks for the help :)
  • Nov 10, 2010, 11:35 PM
    Unknown008

    When is ?

    Then, equate theta to what you have in brackets.
  • Nov 11, 2010, 07:31 AM
    heyyalliee
    Comment on Unknown008's post
    So cos=0 when theta is 90. So then I set up what's in the brackets =to 90?
    Sorry I'm a little confused.
  • Nov 11, 2010, 10:39 AM
    Unknown008

    Yes, that's it :)

    But since you have pi in your expression in brackets, it means you have to work in radians.

    That is 90 degrees in radians?
  • Nov 11, 2010, 11:28 AM
    heyyalliee
    Comment on Unknown008's post
    Okay so 90 degrees in radians is 1.5708. I set 2(pi)(t)/ .74 equal to 1.5708.
    I got t =1.8258. Is this right?
  • Nov 11, 2010, 11:39 AM
    Unknown008

    I'm getting this:



    You might want to keep pi so that you don't have the problem of rounding off.



    Pi cancel out, giving:





  • Nov 11, 2010, 12:12 PM
    heyyalliee
    Comment on Unknown008's post
    Thank you so much for help:)
  • Nov 11, 2010, 12:15 PM
    Unknown008

    You're welcome :)

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