Intensity of Sound: A certain siren radiates sound uniformly in all directions. At a distance of 17 m from the siren, the intensity level is 49 db. How many watts of power does this siren put out? The threshold of human hearing is 1.0 × 10-12 W/m2.
Fill in the blank(s) with the appropriate word(s).
2.9 × 10-4 W
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A blimp is filled with 200 m3 of helium. How much mass can the balloon lift? The density of helium is one-seventh that of air, and the density of air is 1/800 that of water. Consider the mass of the balloon to be negligible.
A. 115 kg B. 214 kg C. 315 kg D. 415 kg E. 37 kg
A spaceship with a constant speed of 0.800c relative to Earth travels to a star that is 4.30 light-years from Earth. How much time for this trip would elapse on a clock on board the spaceship?
A) 3.23 y B) 5.38 y C) 4.40 y D) 5.15 y
If you drove day and night without stopping for one year without exceeding the legal highway speed limit in the United States, the maximum number of miles you could drive would be closest to:
a. 8700. b. 300000. c. 500000. d. 1000000. e. 32000000.
The glass cover for a flat plate solar collector has a spectral transmissivity that may be approximated as shown in the figure. Determine the total effective transmissivity of the glass cover to solar radiation assuming the sun emits that of a blackbody at 5800 K.
GIVEN
• Glass cover for flat plate solar collector with transmissivity as shown.
• Solar radiation at 5800 K assuming it as blackbody.
FIND
• Total effective transmissivity of glass cover to solar radiation.
SKETCH
