1. Are you taking Phys. 1240, The Physics of Sound and Music, for credit
Are you taking Phys. 1240, The Physics of Sound and Music, for credit? A) yes B) no

2. If a tree falls in the forest, does it make a sound? A) yes B) no

3. Professor Allen Hermann
Welcome to PHYS 1240
Sound and Music
Professor Allen Hermann
Cell Phones off
Clickers on

4. 7- 26 8-11 Midterm Exam Final Exam 7-11 L1 Sound, Oscillations,
M T W R F
7-11 L1 Sound, Oscillations,
Waves, Graphs
Ch.1,2,S
7-12 L2 Forces, Mass,
Acceleration, Pressure, Review
of Exponents
Ch.1,2, S
7-13 L3 Restoring Forces,
Energy, Power
7-14 L4 Oscillations and Waves Revisited, Interference,
Waves on a String
Ch.2,4,S
7-17 L5 Sound Waves, Frequency, Pitch, Tone Quality and Harmonics
Ch.2,8,S
7-18 L6 Wave Intensity, Sound Level, Decibels
Ch.5
7-19 L7 The Human Ear, Threshold of Hearing
Ch.6
7-20 L8 Musical Scales, Chords, Intervals
Ch.7,19
7-21 L9 Pythagorean Scales
Ch.18,S
7-24 L10 The Just Scale, The Tempered Scale
7-25 L11 Modes and Non-western Scales
Ch.19,S
7- 26
Midterm Exam
7-27 L12 String Instruments, Harmonics, the Piano
Ch.3,8,10,11
7-28 L13 Vibrating Rods and Membranes, Percussion Instruments
Ch.3,9
7-31 L14 Vibrating Air Columns, Organs, Flutes
Ch.3,12,13
8-1 L15 Brass Instruments
Ch.3,13,S
8-2 L16 Brass Instruments continued, Woodwinds
Ch,3,13,S
8-3 L17 Woodwinds continued, The Human Voice
Ch.3,13,14,S
8-4 L18 Auditorium and Room Acoustics
Ch.15
8-07 L19 Auditorium and Room Acoustics continued
8-08 L20 Electronic Sound, Analog and Digital Devices
Ch.16,S
8-09 L21 Electronic Sound continued, Sampling, CD players and MP3 compression,
8-10 Review for the Final Exam
8-11
Final Exam

5. Grades Mid-term exam………. 25% Final exam……………
Grades Mid-term exam……….25% Final exam……………...35% Homework………………30% Class participation (clicker) …….10% Total……………………….100%

6. Exam dates: Wed. July 26 midterm Fri. Aug.11 final

7. any other instrument with strings any wind instrument
CT 1.0.1
What instrument have you played? (If you have played several, which one the most?)
piano
guitar
any other instrument with strings
any wind instrument
never played any instrument

8. What is sound?
Sound is produced by periodic vibrations, but we need a medium as well for the sound to propagate. Sound is different from light in that it cannot travel in empty space. So an explosion of a distant star would never be heard by us on earth.
Sound travels as mechanical waves, through solids liquids and gases.
So to understand sound, we must understand periodic vibrations or oscillations (the source of sound), the movement of the disturbance which these vibrations cause through a material medium (sound wave), and the reception of this disturbance by, e.g. the ear.

9. Graphs

12. The slope is the speed (discuss the term “velocity”)
The slope is the speed (discuss the term “velocity”). In the last slide the initial slope corresponds to about 180 m traversed in about 3 minutes (180 sec), or the initial speed is about 180m/180 sec= 1 m/s

13. In the period between the sixth and ninth seconds, the student’s speed is a) faster than the initial speed b) slower than the initial speed c) the same as the initial speed

14. PhET simulations you should gain access at phet. colorado
PhET simulations you should gain access at phet.colorado.edu go to Play with SIMS we will do The Moving Man

15. To learn about Periodic Vibrations or Oscillations, we must first learn about Forces

19. A little about Vectors

21. The bigger the weight (force on the spring), the more the spring extends and the more the spring “pulls back”, i.e. the greater the restoring force. We can write the restoring force Fr is proportional to the extension x, Fr=-kx

23. PhET Masses and Springs

24. PhET Pendulum Lab

26. Simple Harmonic Motion
Position x vs. time t
Definition of period T
Definition of amplitude A

27. SHM Systems

31. Let the period be T (in seconds)
Let the period be T (in seconds). The number of times the vibrating source executes SHM in one second (i.e. the frequency, f, units of Hz)) is 1/T. For example, if T is 0.1 s, f is just 1/0.1=10 Hz

32. Frequency and Period f = 1/T or T = 1/f or f T =1
T period, in seconds (s)
f = frequency in Hertz (Hz)
Metric prefixes:
centi- (c), milli- (m), micro- (m)
kilo- (k), mega- (M)

36. CT 2.1.8
Looking at the following waveform, what is the period?
1 sec
2 sec
1 m/s
2 m/s
Not enough information
Amplitude 1 2
time (sec)
ASSUMING IT REPEATS

37. When the frequency is doubled, the period becomes…
CT 2.1.2
When the amplitude of an oscillating object is doubled, the period becomes:
twice as big
1/2 as big
Stays the same
1/4 times as big
Not enough information to decide
When the frequency is doubled,
the period becomes…

38. Pulses and Waves

39. Phet Wave on a String Pulse propagation

42. What choice below best shows the motion of the purple spot?
CT 1.3.3x
I grab the left end of a LONG string and wiggle it up and down. There is a purple painted spot somewhere on the string.
What choice below best shows the motion of the purple spot?
(up and down)
(pushed steadily to the right)
(left and right)
(no motion)
(circular path)

43. PhET Wave on a String Periodic Oscillations or Vibrations

48. Wave velocity for a periodic vibration Let the wavelength be λ and the frequency of the vibration be f. The wave velocity v is just V=λ/T, or V= λf

49. 1 Amplitude Time (sec) The wavelength, λ, is 10 m. What is the
speed of this wave?
1 m/s
7 m/s
10 m/s
15 m/s
None of the above/not enough info?
Amplitude
Time (sec) 1
Propaganda about talking to neighbors?

50. What determines the velocity of a transverse pulse or wave on a string (v=λf simply constrains f and λ) ? The velocity is determined by the tension T ( a force in N) applied to the string, and the mass per unit length μ ( in kg/m).