Give your best short answer in the space provided:
Answers appear in small ilatics beneath question.

1. What is sound?
A pressure wave; a vibration.

2. What is pressure?
The force per unit area. [Newtons/square meter, N/m²]

3. Is there sound in other space? How do you know?
No! There is no medium for the sound vibrations to shake.

4. What effect does temperature have on the speed of sound?
Sound travels faster in higher temperature air.

5. What is frequency?
The number of times in a unit time a wave "wiggles." Frequency = speed of sound/wavelength

6. What is wavelength?
Wavelength is the distance from one point on a wave to a corresponding point on the next cycle of the wave. Wavelength = speed of sound/frequency

7. What is a simple harmonic oscillator?
A simple harmonic oscillator is a mechanical device that oscillates with a single frequency.

8. What does it mean physically when we say that tones are harmonic?
The two tones have frequencies that have a ratio equal to the ratio of two small numbers.

9. What physical attributes determine the timbre of the sound of an instrument?
The harmonic recipe or the amounts of the various overtones determines the timbre of an instrument.

10. Why don’t most percussion instruments have pitch?
The frequency recipe is not harmonic. The overtones are not rational multiples of the fundamental frequency.

11. What are longitudinal waves and how are they different from transverse waves?
Longitudinal waves cause the medium to move along the direction of travel of the wave, back and forth; transverse wave cause the medium to oscillate perpendicular to the direction of motion, that is up and down or left and right.

12. What is the wavelength of a sound wave at 20 C if its frequency is 100 hz?
At 20 C the velocity of sound is 344 m/s. Therefore the wavelength l= v/f = 344 m/s/(100 hz) = 3.44 m.

13. The maximum pressure of a sound wave is 0.3 Pa. What is this pressure in atmospheres?
1 atm = 1.01 ´ 10⁵ Pa. Therefore 0.3 Pa = 0.3 Pa ´1 atm/1.01 ´ 10⁵ Pa = 2.97 ´ 10^-6 atm

14. A pressure of 10 kPa acts against a port hole that is 20 cm by 20 cm. How much force (in Newtons) is exerted on the window?
F = p ´ S = 10 kpa ´ (0.2 m ´ 0.2 m ) = 0.4 kN = 400 N.

15. How much is a Pa (Pascal)?
1 Pa =1 N/m².

16. What is the mathematical relationship between velocity, wavelength and frequency for a wave?
Velocity = wavelength ´ frequency, v = l´f.

17. What are the characteristics of a Simple Harmonic Oscillator?
Any system that has a single natural mode of oscillation, a single frequency and oscillates with a sinusoidal motion.

18. WRR broadcasts at a frequency of 101.1 Mhz. If the speed of light is 3.00 x10⁸ m/s, what is the wavelength of the radio wave?
l = c / f. The speed of a radio wave is the same as the speed of light since they are both E&M waves. l= 3.00 ´10⁸ m/s / (101.1 ´ 10⁶ hz) = 2.97 m.

19. What is the frequency of oscillation for a Simple Harmonic Oscillator consisting of a mass of 2.5 kg and a spring of spring constant 500. N/m?
f = 1/(2p ) Ö (K/m) = 1/( 2´ 3.1416) Ö(500 N/m)/(2.5 kg) =2.25 hz.

20. In a solid material we determine that the wavelength of a 440 hz sound wave is 2.27 m. What is the velocity of sound in this medium?
v = l f = (2.27 m)´ (440 hz) = 999 m/s.

21. If a pop bottle has a volume of 250 ml and it produces a tone of 190 hz when you blow across the throat of the bottle, what will be the approximate frequency if you add 125 ml of water?
For a Helmholz resonator the frequency is inversely proportional to the square root of the volume in the bottle. Thus, by adding 125 ml we have cut the volume by a factor of ½. The frequency must therefore increase by a factor of the reciprocal of the square root of ½. Thus, f = 190 hz /( Ö 1/2) = 190 hz/.7071= 269 hz.

22. You are watching the grain wave back and forth in the field. If you hold a meter stick steady near a stalk you see that a particular wheat stalk moves forward to 35 cm and back to a reading of 21 cm twice per second. What is the displacement amplitude? What is the frequency? What is the period? Is this a transverse or longitudinal wave?
A = (0.35 m- 0.21 m)/2 =0.075 m; f = 2 hz; P = 0.5 sec; Longitudinal wave.

23. If you have three masses coupled together with springs. How many modes of oscillation can you have?
Three mass means three degrees of freedom and three natural modes of oscillation.

24. You observe the frequencies 520 hz and 780 hz in a sound sample. What is the fundamental frequency of this harmonic series, and what harmonic are each of these two frequencies?
Notice that 780/520 = 3/2. Thus 520 = 2 ´ 260 and 780 = 3 ´ 260. Thus 520 is the second harmonic of 260 hz and 780 is the third harmonic of 260 hz.

25. What are the frequency ratios for the following harmonics?
f₂/ f₁ = 2
f₃/ f₁ = 3
f₄/ f₁ = 4
f₄/ f₂ = 2

26. What frequency ratio is an octave?
An octave = a frequency ratio of 2. The seciond harmonic is one octave higher than the fundamental.

27. What physical characteristics distinguish a musical "ding!" with pitch from a percussive "bang!" without pitch?
The "ding" has harmonics that are integral ratios of the lowest frequency. The higher frequency components of the frequency spectrum do not have whole number ratios to the lower frequencies.

28. Why did a square wave sound similar to a clarinet?
Both the square wave and the clarinet only contain odd harmonics.

29. What is Ohm’s Law for acoustics and why is it important?
The human ear is insensitive to phase of the sound it hears.

30. What condition is necessary for two oscillators to be in resonance?
The frequency of the two oscillators must be nearly the same.

31. Why does the sound change with time after a bell is struck?
The higher frequency modes of oscillation damp out more quickly than the lower frequency ones.

32. Where does sound energy ultimately go?
Sound energy ultimately dissipates as heat, the random motion of atoms and molecules.

33. If I drag a chair 1 .5 m across the floor and am exerting a constant force of 20 N, how much work have I done?
Work is force multiplied times the distance move. Thus work = 20 N ´ 1.5 m = 30 J.

34. If a 100W light bulb is left on for 1 hr. How many kW-hrs of electric energy is used and how many Joules is this?
A kW-hr is the power (in kW) multiplied by the time (in hours). Thus, the energy used was 0.100 kW ´ 1 hr = 0.1 kW-hr. 1 kW-hr = 1000 J/s ´ 3600 sec/hr = 3.6 MJ. Thsu, 0.1 kW-hr = 360 kJ.

35. On a very hot day in Texas in July the temperature can get to 40 C. What would the velocity of sound be on such a day?
v = 344 m/s + 0.6 (T -20 C) m/s = 344+0.6(40-20) = 344+ 0.6(20)= 344+12 =356 m/s.

36. When the comet Shoemaker-Levy 9 smashed into Jupiter a few years ago it hit with a tremendous impact. Why couldn’t we hear it here on earth?
There is no air in the space between earth and Jupiter, therefore there is no medium for the sound ot travel through. So the sound could not get to us. On Jupiter, however, there was a very loud boom, I am sure.

37. A car is speeding down the freeway at about 77 mph (34.4 m/s). What fraction of the speed of sound is this approximately?
(34.4 m/s)/(344 m/s) = 0.1; about 1/10 the speed of sound.

38. A jet airplane cruises at about 385 mph (172 m/s). What fraction of the speed of sound is this?
(172 m/s) /(344 m/s) =0.5, about ½ the speed of sound.

39. If a beaker is broken by a singer’s voice, what acoustical principle is at work?
Resonance.