1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Waves (Sinos., Interference, etc.)

  1. Oct 26, 2005 #1
    1.) Suppose the equation for the left end of a string is y = 0.1sin((pi)x - (pi)t).
    What would be the equation for the motion of the point on the string at x = 1.5m to the right of the left end. Apparently, x is set to zero to yield the equation y = 0.1sin(-(pi)t). But I don't understand why. Any explanation is helpful.

    2.) If i have determined the phase difference of a wave to be 2.0 rad, and I also have angular frequency (4 rad/s), how would i determine the phase in terms of time? Apparently its phase / angular frequency (so, 0.5sec), but I don't understand this conceptually.

    3.) Two speakers are driven in phase by a common oscillator at 800Hz and face each other at distance of 1.25m. Locate the points along a line joining the two speakers where relative minima of sound pressure amplitude would be expected.

    Once again, I am solving for the points where there is destructive interference. In this case, I believe that it would be the nodes. I could solve for wavelength via [itex]\frac{v}{f}[/itex] Thus wavelength equals 2.33m. Where do i go from there? How do i find the coordinates of the nodes?
  2. jcsd
  3. Oct 27, 2005 #2


    User Avatar
    Gold Member

    If you have the wavelength then you just have to find the points (P)between the speakers (S1,S2) were P(S1-S2) is a multiple of half the wavelength ((n-0.5)(wavelength/2))
  4. Oct 27, 2005 #3
    Thank you.

    Can anyone try to solve the first two problems?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook