physics

A source of sound (1000 Hz) emits uniformly in all directions. An observer 3.19 m from the source measures a sound level of 39.2 dB. Calculate the average power output of the source.

  1. 👍
  2. 👎
  3. 👁
  1. Use the decibel level definition to compute the intensity in units of Watts per area. Multiply that number by 4 pi R^2 (the area of a sphere of radius R) to get the total power output.

    1. 👍
    2. 👎
  2. I = 39.2/1.0 x 10^-12
    = 3.92 x 10^-11 W/m^2 x 4 pi (3.19^2m^2)
    = 5.01e-9 W

    i got the wrong answer

    1. 👍
    2. 👎
  3. You did not use the correct logarithmic formula that relates decibels to intensity.

    To review it, see:

    http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/sound/u11l2b.html

    At 39.2 dB, the sound intensity level is 10^3.92 = 8318 times above the reference (hearing threshold) value of 10^-12 W/m^2. So the value of intensity you must use is 8.32*10^-9 W/m^2

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    A rocket in a fireworks display explodes high in the air. The sound spreads out uniformly in all directions. The intensity of the sound is 3.14 x 10-6 W/m2 at a distance of 121 m from the explosion. Find the distance (in m) from

  2. physics

    An audio speaker at a concert emits sound uniformly in all directions at a rate of 100 W. (i) Calculate the sound intensity experienced by a listener at a distance of 8 m from the speaker. The listener moves back from the speaker

  3. Physics(Please respond)

    A source emits sound uniformly in all directions. There are no reflections of the sound. At a distance of 12 m from the source, the intensity of the sound is 1.7 × 10-3 W/m2. What is the total sound power P emitted by the source?

  4. physics

    A rocket in a fireworks display explodes high in the air. The sound spreads out uniformly in all directions. The intensity of the sound is 1.90 10-6 W/m2 at a distance of 120 m from the explosion. Find the distance from the source

  1. physics PLEASE HELP

    A source emits sound uniformly in all directions. There are no reflections of the sound. At a distance r1 from the source the sound is 6.5 dB louder than it is at a distance r2 from the source. What is the ratio r1/r2?

  2. physics

    to an observer the pitch of the stationary source of the sound appears to be reduced by 20% if speed of sound is 340m/s then sped and direction of 5he observer is options 1.68 m/s away from the observer 2.96 m/s away from the

  3. Physics

    A tiny source emits sound uniformly in all directions. The intensity level ar a dist. Of 2m is 100dB. How much sound power is the soure emitting?

  4. Physics

    as observer travelling with a constant velocity of 20m/s passes close to a stationary source of sound and noticed that there is a change of frequency of 50Hz as he passes the source. What is the frequency of the source? (speed of

  1. physics

    at a distance of 3.8 m from a siren, the sound intensity is 3.6 x 10-2 W/m2. Assuming that the siren radiates sound uniformly in all directions, find the total power radiated.

  2. physics

    Ige confused, the truck driver sound the horn of the truck, which has a frequency of 260HZ. The speed of sound in air is 340m/s. an observer hears the sound while traveling in a bus toward the truck at a speed of 30m/s. a) what is

  3. Physics

    1. A train whistle has a frequency of 1000 Hz. If the train is speeding at a velocity of 60 km/h past a stationary railroad crossing attendant, what is the apparent frequency a) as the train approaches him, b) as it moves away

  4. Physics

    1)As a sound source moves away from a stationary observer, the number of waves will. A)increase B)decrease C)remain the same D)need to know the speed of the source (answer:decrease.) As the detector recedes from the source, the

You can view more similar questions or ask a new question.