The Physics
Opus in profectus


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  1. Determine the loudest sound possible (the sound with the greatest pressure level) in decibels…
    1. in the air on the surface of the Earth
    2. in the ocean near the equator, 1,000 m below seal level (in the equatorial SOFAR channel)
  2. Normal conversation has an intensity level of around 60 dB. Determine the…
    1. pressure amplitude
    2. density amplitude
    3. displacement amplitude
    4. velocity amplitude
    5. acceleration amplitude
  3. A sound wave is traveling from the air to the water on a day when both are at 15 °C.
    1. How does the intensity of the sound wave in air compare to the same sound wave in water?
    2. By how many decibels is the sound intensity level reduced?
    3. Where does the excess energy go when a sound wave is incident upon an air-water interface?
    Properties of air and water at 15 °C
    air water
    density (kg/m3) 1.225 0,999
    speed of sound (m/s) 0,340 1,497
  4. Write something completely different.


  1. Determine the maximum displacement of a gas molecule in the air from a 1,000 Hz tone with an intensity of…
    1. 1 pW/m2 (threshold of sensation)
    2. 1 W/m2 (threshold of pain)
  2. Unlike the threshold of hearing where 20 μPa corresponds to a sound intensity level of 0 dB by definition, there is no standard value for the threshold of pain. (Assume room temperature conditions.)
    1. Some sources claim 20 Pa as the threshold of pain.
      1. How many decibels is this?
      2. Determine the corresponding intensity.
    2. Some sources claim 1 W/m2 as the threshold of pain.
      1. Determine the corresponding pressure amplitude.
      2. How many decibels is this?
  3. What pressure level in decibels corresponds to a maximum dynamic pressure of…
    1. one atmosphere
    2. one thousandth of an atmosphere
    3. one millionth of an atmosphere
    4. one billionth of an atmosphere
    5. one trillionth of an atmosphere
  4. Determine the loudest sound possible (the sound with the greatest pressure level) in decibels in the atmosphere on the surface of Mars.