As measured from centre ice, a single wildly cheering hockey fan can produce a sound intensity level of 60dB. What sound intensity level would be produced by
20 000 cheering fans?
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If sound waves travel through the ground with an average speed of 6150 m/s and a powerful explosion occurs 5.00kn away, how much time will elapse between when you feel the vibration from the explosion and hear the explosion? Use v=344m/s for the speed of sound in air.
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You pick up two metal rods that look the same and appear to have the same mass. However, when you strike the first rod, it produces a sound that has a much higher frequency than the second rod. What does this result tell you about the speed of sound in the two rods?
THANKS.
1. L = Lₒ + 10•logN = 60 +10•log(20000) =60 +10•4.3 =103 db.
2. t1 = s/v1 = 5000/6150 =0.81 s.
t2 = s/v2 = 5000/344=14.53s.
Δt =14.53 – 0.81 =13.72 s.
3. The frequency is set by the oscillating body which sets up the sound waves. The speed of the waves is determined by the elastic/inertial properties of medium and the wavelength.
λ = v/f (the higher wavelength the higher frequency)
The speed of sound doesn’t depend on frequency.
To calculate the sound intensity level produced by 20,000 cheering fans, we need to understand that sound intensity level is measured in decibels (dB) on a logarithmic scale. Each increase of 10 dB represents a tenfold increase in sound intensity.
Given that a single fan produces a sound intensity level of 60 dB, we can calculate the combined sound intensity level of 20,000 fans by using the formula:
20 * log10(N),
where N is the number of fans.
20,000 fans can be represented as N = 20,000. Plugging this value into the formula, we get:
20 * log10(20,000) = 82 dB.
Therefore, the sound intensity level produced by 20,000 cheering fans is approximately 82 dB.
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To determine the time elapsed between feeling the vibration from the explosion and hearing it, we need to consider how sound travels through different mediums.
Given that the average speed of sound through the ground is 6150 m/s and the distance between you and the explosion is 5.00 km (which can be converted to meters as 5.00 km * 1000 m/km = 5000 m), we can calculate the time using the formula:
time = distance / speed.
Plugging in the values, we get:
time = 5000 m / 6150 m/s = 0.813 seconds.
Therefore, approximately 0.813 seconds will elapse between feeling the vibration from the explosion and hearing the explosion.
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If the first metal rod produces a sound with a much higher frequency than the second rod when struck, it implies that the speed of sound in the two rods is different.
The speed of sound is determined by the properties of the medium through which it travels. In this case, since both rods appear to have the same mass, the difference in sound frequency indicates that the rods have different material properties. The first rod likely has a higher speed of sound, while the second rod has a lower speed of sound.
The sound frequency is directly related to the speed of sound in a material. Higher frequencies indicate a higher speed of sound, while lower frequencies indicate a lower speed of sound.
Therefore, the result tells us that the speed of sound in the first rod is higher than that in the second rod.