Download “Physics through Music”

“Physics through Music”
Examination Review
May 8, 2017
What have we covered in the books? (Notice that not all material comes from the textbooks so
you need to review the lecture notes as well.) There is a lot of relevant information at
http://www.science.howstuffworks.com
You will have to search for the right topics.
General Topics
Music Stuff to Read
Johnston
Chapters 1,2
Interlude I , pages
Some of this
41-47
material comes from Chapter 3, most of it
previous work. This Chapter 4, 88-100
material will be
(remainder of the
completed before
chapter is
the next exam.
interesting)
Chapter 5 all
Interlude 4,152-166
Chapter 6,178-180,
183-191
(not all covered in
class)
Chapter 7, 221-244
Interlude 6, 247-260
Interlude 8,319-338
Appendix 2,4
Chapter 8 268--286
Chapter 1
Chapter 6
Chapter 15
Chapter 16
Chapter 17
Chapter 18
Chapter 19
Chapter 20
Bolemon
Bolemon Problems
Pages 16-17
All of chapter
except forces at
angle
19-21
Same as before. We
actually covered this
on the previous test
but you still need to
understand energy.
Through Pg. 290
1-7
Pg 300-305,308-312
1,2,4-6,11,12
Pg 318-324,3281-7
330,
Pg. 338-351
most
Pg. 356-363
Pg. 382
The relationships between frequency, period and wavelength should be recalled from the
material covered on the last exam. It clearly applies to the new material. Most of the
REVIEW FOR EXAMINATION #3
new material is more qualitative in nature so that not too many (if any at all) formulas
have been introduced.
You are expected to have read all of the material described in the table above and you
should be able to reproduce the salient features. Concentrate on material that I covered in
the classroom. This will be what will be stressed on the exam.
There will be no formula sheets used for this exam since there were only a few formulas.
What you need will, except for the most obvious cases, will be supplied as a part of the
question.
The material covered on this exam is reflected by Lectures 13-22, all of which appear on
this website. The highlights of each of these lectures are as follows.
Lecture #13
This lecture was a completion of the previous discussion of the guitar. Note that standing
waves were once again stressed (read about how they are formed in Johnston). The
function of the bridge as well as the timbre of the instrument was covered briefly. The
extension to the violin then took place. Make sure that you fully understand the last slide
(What happens when …) of this lecture. Know what it means and how to interpret it.
What are the wavelengths and frequencies for each diagram?
Lecture #14
Again we discussed the frequencies that were stable on stringed instruments. I must
think this to be an important topic. We discussed how toned are added and how the fifth
looks as compared to an interval not quite a fifth sounding together. Consonance was
started here with two consonance curves being presented which will rear their ugly heads
in a later lecture.
Ptolemy’s contribution of the “Just Scale” was covered here and in the next lecture. Note
the complex instrumentation required because the Just scale didn’t allow for the change
of musical keys. This let to equal temperament. Know what the scales were if not
exactly how to calculate either the frequencies of either one.
Lecture #15 included the results of test #2.
Again, the musical scale was described leading to a discussion of the flute. This material
is well covered in the Johnston text. Understand where the nodes and antinodes are for
resonance and understand the pressure node vs. the velocity node. They are different and
some graphs appear that point out the differences. Both closed and open ended tubes
(flutes) are important here and in the lectures on voice.
Lecture #16
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REVIEW FOR EXAMINATION #3
This lecture discussed the resonances and the modes of vibration of an instrument.
Understand the three guitar figures … the vibration modes as well as the tones that come
out. Can you calculate the frequency and wavelength or period from the figure labeled
“Sound from the Guitar”? You should be able to. We then discussed the modes of
vibration of the bar and the drum and pointed out that the drum is NOT harmonic. But
the drum has clear vibrational modes. Diagrams are included.
Lecture #17
The next topic concluded drums and jumped into some physics of power. Power was
defined and we discussed how the power per unit area decreases with the square of the
distance from the source. We calculated how much energy per unit time per unit area
arrives at the ear from a sound source a distance away from it. Know how to do this.
You also should know what a log is and be able to work with powers of 10 (although the
treatment will be minimal, if at all). Know the definition of the decibel. Know what the
acoustic power is and the range of human hearing.
Lecture #18
Again, power is stressed with some overlap of log, dB and range of hearing. We also
cover the frequency range of hearing and you should know the salient facts. Know the
limits and the sizes of things. What is the minimal level of hearing? The threshold of
pain. The dynamic range between them.
We then turned to the major parts of the ear. Know how the cochlea deciphers the
frequency from the sound the ear receives. Know about the damage that can occur from
loud music and the role of the hair cells.
Lecture #19
We continued with hearing and stressed how the basilar membrane works and what it
does. We then jumped into the processes that take place between the source of sound and
the ear. Know about reflection, absorption, interference, diffraction, phase differences
and finally, beats.
Lecture #20
More of the same. Review “Consider this Table”, roughness, and how the old
amphitheaters were designed. The band shell is another example. How does the
“whispering gallery” work? The parabolic receiver?
Huygen’s principle allows the understanding of diffraction (well, …) and we looked at
what happens with small holes in walls vs. larger ones. Next we jumped into room
dynamics and discussed reverberation, how it is measured and how the various properties
of the room determine the reverberation time. We looked at the reflective (or absorptive)
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REVIEW FOR EXAMINATION #3
properties of various materials and finally what reverberation times are needed for
various types of performance. Rock bands were not included.’
We then finished up the consonance material. The book is pretty good on this stuff. A
quick review of the cochlea shows how important this topic really is! Finally, a trip to
the brain and we had music. Beethoven, in particular.
Lecture #21
No need to review this section since it was stolen completely from the textbook.
Understand how the voice is produced by a combination of resonance, puffs of air and the
Fourier Theorem that was discussed previously. Know how the vocal folds work
(remember that funny noise??).
Recognize how the volume of the room and the absorption of the walls effect the
reverberation time.
Lecture #22
The Human Voice was discussed here. Know how the tone (frequency) is produced and
where in the “vocal tract” it comes from. The function of the lungs, vocal chords, etc. in
voice production. Fourier’s Theorem raises its ugly head again. Do you know it yet?
Types of voice and rough frequency ranges. Hey guys … wanna be a castrato? What
was this and why was it a good career in those days?
Make sure you know about open tubes and the notes and the frequencies that can be
produced by such a structure.
Lecture #23
Most of this is in the Bolemon text. The nature of dead cats and their contribution to
understanding electricity. Charges, two types, and how they interact. Moving charge is
the negative electron. Know what induction is and why the charged rod moved a neutral
2 x 4 board.
Lecture #24
We finished charged objects and introduced Coulomb’s Law for the force between
charges. Know that it is an inverse square law. We looked at balloons, bits of paper and
how they were effected by static charges. We discussed types of materials as well …
insulators and metals. We touched on the Van der Graaf machine and demonstrated how
it works. We only lost one student.
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REVIEW FOR EXAMINATION #3
Lecture #25
Again, mostly in the book. We discussed capacitors, batteries, and resistors. OHM’S
LAW (very important). We discussed circuits with light bulbs (there is a question on
this). The music application here was the beginning discussion of loud speakers and how
they work.
Lecture #26
Magnetism and how currents are made with wires moving through magnetic fields. We
looked at magnets, N & S poles. Where does the compass point?? What is a dynamic
microphone?
Lecture #28
We finished microphones and discussed amplifiers, the electric guitar and how it works
and began to wrap things up.
Lecture #29
The last things we discussed was the synthesizer and final digital applications of
electronics to music and recording. The CD and a little about how it works. MP@ …
what is it? What is a “bit”?
That’s about it. Be sure to review the early stuff about “Supe” and how he handled his
girlfriend’s falling problem. How do things fall, acceleration, gravity.
GOOD LUCK
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