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: Sound waves from a speaker

  1. Jun 7, 2010 #1
    A block with a speaker bolted to it is connected to a spring having spring constant k= 20.0 N/m as in Figure P17.40. The total mass of the block and speaker is 5.00 kg, and the amplitude of this unit's motion is 0.500 m. (a) If the speaker emits sound waves of frequency 440 Hz, determine the highest and lowest frequencies heard by the person to the right of the speaker. (b) If the maximum sound level heard by the person is 60.0 dB when he is closest to the speaker, 1.00 m away, what is the minimum sound level heard by the observer? Assume that the speed of sound is 343 m/s.
    2.gif

    The solution
    1.png

    Can some one tell me what are the formulas they used in part a ? I can't find them in my book (Halliday, fundamentals of physics)
     
  2. jcsd
  3. Jun 7, 2010 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi Hitman6267! :smile:

    The first is KE + PE = constant (and PE = 1/2 kx2).

    The second is the standard formula for frequency at different speeds.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook