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Sound & Temperture Questions? please help me

  1. Jul 27, 2007 #1
    Sound & Temperture Questions??? please help me!!

    1. A sound wave radiates from a source to all directions, If the power of the sound is 200 watts, then the intensity of the sound wave 100m from the source is?


    2. The bulk modulus of water is 0.210 x 10^10 n/m^2 and the density is 100 kg/m^3. The velocity is?


    3. The young’s modulus of copper is 1.10 x10^11 N/m62. If density is 8,890 kg/m^3 then what is the velocity?


    4. The sound of a jet engine is given as 120 dB. What is the intensity of the jet sound wave?


    5. A 3.0 organ pipe is open at both ends. The velocity of sound is 331 m/s. What is the wavelength of the lowest frequency?


    6. Compared to the speed of a 100Hz sound, the speed of a 200Hz sound through air is:?


    7. If the temperature changes by 36 degrees F, then what is the change in temp. in Celcius.


    8. A brass rod is 25.0 cm long at a temp of 20.0 degree C. The of brass is 19.0 x 10^-6 degree C. If the temp. changes to 25 degree C, then the increase in length of the brass rod is:?


    9. The temp. of a copper cube increase by 35.0 degree C. The is 17.0 x 10^-6 degree C. The fractoual change in volume is:?


    10. One mole of an ideal gas has a volume of 0.0224 m^2 and a pressure of 101.3 x 10^3Pa. What is the absolute temp. of gas?



    11. At what temp. are the celcius and Farenheit temp the same?

    12. An ambulance is generating a siren at a frequency of 2,000 Hz. The velocity of sound is 345.0 m/s. The observer and the ambulance are traveling toward each other at a velocity of 24.00m/s. If the observer is stationary what is the frequency of the siren perceived by the observer?

    13. An ideal gas at a temp. of 34 degree C has a pressure of 2.00 atm and a volume of 2.101 liters. What is the temp. if the pressure is halved (1/2) and the volume is tripled?

    14. What is the root mean squared velocity of the helium atom in one mole of an ideal gas at a pressure of 2.00 atm and a temp of 30 degree C (He=4u)?

    15. What is the average kinetic energy per particle in 1.00 mol of an ideal gas at a pressure of 1.50 atm and a temp of 20 degree C?
     
  2. jcsd
  3. Jul 27, 2007 #2

    cristo

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    You need to show some work before we can help with obvious homework questions.
     
  4. Jul 27, 2007 #3
    not homework questions...study questions for a test which i have no idea how to do...can someone help me with some equations or something? if not, DONT REPLY! thanks
     
  5. Jul 27, 2007 #4
    what is the formula to solve this equation??

    1. A sound wave radiates from a source to all directions, If the power of the sound is 200 watts, then the intensity of the sound wave 100m from the source is?
     
  6. Jul 27, 2007 #5

    ZapperZ

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    1. Whether it is homework or not, we have a HW/Coursework forum where these questions should be posted.

    2. It is OUR POLICY that we do not simply do the work for you or give you the answer. You have to show what you know and where you got stuck. This is the ONLY and most effective way of learning, and it is something we adhere to in here.

    Zz.
     
  7. Jul 27, 2007 #6
    bulk modulus

    if you know bulk modulus and density how do u find the velocity?
     
  8. Jul 27, 2007 #7

    Doc Al

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    The velocity of what? What are you talking about?

    ...ah... speed of sound, perhaps? Read this: Speed of Sound
     
    Last edited: Jul 27, 2007
  9. Jul 27, 2007 #8

    mgb_phys

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    A couple of clues then -
    Intensity has units of w/m^2
    The sound spreads out into a sphere, how many m^2 are there on the surface of a sphere 100m in diameter?
     
  10. Jul 27, 2007 #9
    ok i have that in terms of v= sqrt of. a measure of the restoring force (B) / a measure of the inertia (p) but sqrt (0.210*10^10/100) is not giving me the answer i need ?? am i missing something?
     
  11. Jul 27, 2007 #10
    sqr. root (0.210*10^10 n/m^2/100kg/m^3) ???
     
  12. Jul 27, 2007 #11

    Doc Al

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    Why don't you post the exact problem you are trying to solve.
     
  13. Jul 27, 2007 #12
    because someone told me i could not do that and no one would help me if i did that?? will u help me?? the problem is... the bulk modulus of water is 0.210x10^10n/m^2 and the density is 100 kg/m^3. What is the velocity?
     
  14. Jul 27, 2007 #13
    Thermal Expansion

    25cm brass rod, alpha of brass 19.0 *10^-6, temp change 20-25, what is the increase in length of the brass rod? WHAT FORMULA IS THIS??
     
  15. Jul 27, 2007 #14

    Astronuc

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    Presumably one knows the formula for converting °F to °C or °C to °F.

    In problem 11, let TF=temperature in Fahrenheit and TC=Temperature in Celsius, and using the conversion formula, make use of TF=TC for two simultaneous linearly independent equations with two unknowns.

    Hyperphysics has many of the formulas required for these problems, e.g.
    http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/kintem.html

    Problem 9 seems incomplete, or 17.0 x 10-6 °C-1 is the thermal expansion coefficient.
    http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thexp.html
     
  16. Jul 27, 2007 #15

    ZapperZ

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    Please do not post MULTIPLE TIMES all over PF! You are posting either identical or similar questions separately. STOP DOING THIS!

    Zz.
     
  17. Jul 27, 2007 #16

    cristo

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    Did you read the link that Doc Al gave you in his post above? This gives the formula you need to use. Again, we're willing to help you here at PF, but you need to put some effort in. Surely reading a link that someone provides you with is not that difficult.
     
  18. Jul 27, 2007 #17

    Astronuc

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    Ostensibly, one's physics textbook would have chapters on each of the various topics related to the problems, otherwise I am puzzled as to why one would be trying to solve such problems without familiarity with the subjects.
     
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