posted by Veronica .
1. How many nodes (counting nodes at the ends), are present in the displacement oscillations of an open-closed tube (oboe) that vibrates in its fourth harmonic?
a) 3 nodes
b) 4 nodes
c) 5 nodes
d) 6 nodes
e) An open-closed tube has no 4th harmonic
2. At a distance of 30 m the noise from the engine of an jet has an intensity of 130 dB. At this level, you will be in pain and your ears will hurt. That's why this intensity is know as the "pain threshold". How far do you have to move from the jet in order for the noise to drop down in intensity to 57.9 dB, a level comparable to that of a spoken conversation?
3. An out-of-tune violin plays an "A" note of 446 Hz. At the same time, a tuning fork vibrates with a true-A of 440 Hz. The frequency of the beats produced (intensity fluctuations) is ...
***Hint: The frequency of the beats is not the same as the frequency of the envelope.***
a) No beats are produced in this situation
b) 1.5 beats per second
c) 3 beats per second
d) 6 beats per second
e) 12 beats per second