Part A: Suppose you want to build a musical instrument with a hollow pipe that i
ID: 1559563 • Letter: P
Question
Part A:
Suppose you want to build a musical instrument with a hollow pipe that is open at both ends. You will make it oscillate by blowing air across one end. If it has length 1.21. What frequency will it resonate at in Hz? Assume the speed of sound in warm moist air is 340 m/s?
Part B:
The resonant frequencies of the lowest frequency strings of a guitar are 82.4 Hz (E) and 110 Hz (A). Where would you depress the E string so that it had the same frequency as the next lowest string, the A at 110 Hz?
1st fret
2nd fret
3rd fret
4th fret
5th fret
f. It is not possible to raise the frequency by shortening a string
Part C:
Match the string with its note. While there is a range of tensions used to tune the strings, they are roughly the same ad differ by only 20%. The strings shown are from a real guitar used to play acoustical music. Masses are given in grams per meter.
330 Hz
247 Hz
196 Hz
147 Hz
1.03 g/m
0.309 g/m
1.62 g/m
0.477 g/m
Part D:
While attending a large fireworks event with music, you decide to stay 1 kilometer away because of the crowds. However you have a good view, and you can still hear the booms, as well as the music. Given a speed of sound on a warm moist summer night of 340 m/s, select those that apply.
The music is out of phase with the fireworks and occurs about 6 seconds early
The music is out of phase with the fireworks and occurs about 6 seconds late.
The booms are so loud they occur at the same time as the flash of fireworks explosion.
The booms follow the flashes you see by about 6 seconds.
a.1st fret
b.2nd fret
c.3rd fret
d.4th fret
e.5th fret
f. It is not possible to raise the frequency by shortening a string
Explanation / Answer
Part A)
L = length of pipe = 1.21 m
V = speed of sound = 340 m/s
fundamental frequency is given as
f = V/(2L)
inserting the values
f = 340/(2 x 1.21)
f = 140.5 hz