posted by HelpMeWithPhysics on .
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?
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.
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?
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.