Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Wave on a string problem

  1. Feb 5, 2008 #1
    1. The problem statement, all variables and given/known data

    If y(x,t)=(6.0mm)sin(kx+(600rad/s)t+[tex]\Phi[/tex]) describes a wave travelling along a string, how much time does any given point on the string take to move between displacements y= +2.0mm and y= -2.0mm?



    2. Relevant equations

    I think y(t)=ym sin([tex]\omega[/tex]t) ?



    3. The attempt at a solution

    well if I plug in 2.0mm for y, 6.00mm for ym and 600rad/s for [tex]\omega[/tex] I come up with the equation 2.0mm=6.00mm sin (600rad/s * t). Where do I go from here? are my assumptions correct so far?

    Other things as I am thinking- 600rad/s is about 95.5Hz so each complete cycle from +6mm to -6mm should take .01s or so, so my answer should be less then that.

    Thanks for your help
     
    Last edited: Feb 5, 2008
  2. jcsd
  3. Feb 5, 2008 #2
    anyone?
     
  4. Feb 5, 2008 #3
    I think I have it- if I then take

    sin[tex]^{}-1[/tex](2/6)=600*T1?

    sin[tex]^{}-1[/tex](-2/6)=600*T2?

    then [tex]\Delta[/tex]T is T1-T2?

    does anyone have any input here?
     
  5. Feb 5, 2008 #4
    pretty sure I've got it-

    y1(x,t)=ym*sin(kx+600t1+[tex]\Phi[/tex])

    2.00mm=6.00mm*sin(kx+600t1+[tex]\Phi[/tex])

    sin[tex]^{}-1[/tex](1/3)=kx+600t1+[tex]\Phi[/tex]

    y2(x,t)=ym*sin(kx+600t2+[tex]\Phi[/tex])

    -2.00mm=6.00mm*sin(kx+600t2+[tex]\Phi[/tex])

    sin[tex]^{}-1[/tex](-1/3)=kx+600t2+[tex]\Phi[/tex]

    so...
    [sin[tex]^{}-1[/tex](1/3)]-[sin[tex]^{}-1[/tex](-1/3)]=(kx+600t1+[tex]\Phi[/tex])-(kx+600t2+[tex]\Phi[/tex])

    and...
    [sin[tex]^{}-1[/tex](1/3)]-[sin[tex]^{}-1[/tex](-1/3)]=600t1-600t2

    finally,

    ([sin[tex]^{}-1[/tex](1/3)]-[sin[tex]^{}-1[/tex](-1/3)])/600=t1-t2

    do the math and [tex]\Delta[/tex]t is .00113s

    I think this is solved
     
  6. Jul 27, 2009 #5
    no one ever responded to this guys problem, and now i'm actually trying to solve this as well and i tried doing the method he ended up using but i am not getting a correct answer. Although his method for the most part looks right and makes sense to me, the only thing I figure would be the problem is that x isn't a constant so they should cancel i don't think....but i'm not sure what else to do with so many unknown variables...any help???
     
  7. Jul 27, 2009 #6
    oops nevermind...my calculator was in degree mode instead of radian mode
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Similar Discussions: Wave on a string problem
  1. Waves in a string (Replies: 1)

  2. Waves on a string (Replies: 4)

  3. String wave problems (Replies: 21)

Loading...