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Homework Help: Energy Transfer of Waves/Sound

  1. Aug 4, 2003 #1
    Ah....yet more questions...

    These are some questions from my last assignment for the semester- I figured I would finish it all up before I head off the competitions for the next month. Again- I feel fairly confident with my answers- but I have had so much trouble in physics that I sometimes second-guess my work. Any help and/or comments would be great!!!

    1) True or False. The period of a body in simple harmonic motion is independent of its mass.

    True

    2) True or False. At resonance, very little energy is required to obtain a larger amplitude.

    True

    *How exactly can you tell the difference (from drawings) as to whther or not they show complete of partial constructive/destructive interference? How do the direction of the forces make a difference?*

    3) The air temperature is 10* C. What is the wavelength of a sound emitted by a tuning fork having a frequency of 440 Hz?

    Using the equation V= (wavelegth)(frequency) as my base I first decided to find the frequency. To do this I used 331+.6(10) which is 337 m/s. I then substituted this into the equation and solved as follows: 337= w (440)
    337/440= .765 m
    is this correct?

    4) The wavelength of a wave generated by an AM broadcasting station is 405 m. In KHz, what is the frequency of the wave?

    Using 331 as the base velocity I used 331= 405 f
    331/405=.817= 817 KHz
    I think this sounds about right....

    5) A sound pulse is directed from one airplane to another that is 1255 m away. A reflected pulse is detected 8 seconds after the original pulse was transmitted. What is the temperature of the air surrounding the plane?

    V=d/t......d= 1255(2)=2510m
    t= 8 s
    V= 2510/8= 313.75
    I then use 331 + .6x= 313.75 to find the temperature.
    The resulting answer is -28.75 * C.....is this right?

    6) A Wave having a frequency of 2 Hz is generated along a spring. The wave has a wavelength of .457 m. What is the speed of the wave along this spring?

    Here I am presuming "speed" to mean velocity. V= 2(.457)= .91 m/s
    Does this sound correct?

    7) /a sonar signal of frequency 1005 Hz has a wavelength of 145 cm in water, What is the velocity in water?

    Again I use the equation V= Wavelength(F)
    145 cm= 1.45 m so V= (1005)(1.45)
    The answer is 1.46 x 10^3 m/s; correct?

    Thank you so much for your time!
     
  2. jcsd
  3. Aug 4, 2003 #2
     
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