Sound

Hello:-)

Today, we watched a video about:

-Temperature, Material and Speed of Sound
-Doppler Effect on Sound
- Sound Barrier/Bending

and to jot down 10 interesting things about it.

Sound Test on Friday, 17th of October.

Nicolias to scribe for tomorrow!

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Oct. 8, 2008

Hello everybody!! it's me Ramina and I'm the scribe for today's class.
Today we did our labs about the Speed of Sound. In this lab we examined the differences between ice water and hot water.

First of all we measure the temperature of each water, then strike the tuning fork hard and soft, while striking it we examined the differences between loudness and softness of the sound such as the wavelength, speed, and the length of the sound.

Here is the lab worksheet that we just did, in case you need it..



I'm sorry if it's lack of info. :)

Ahmm,,
also reminder...
don't forget to finish the worksheets about sound that we got from ms. K :)
we will be checking it tomorrow...

next scribe is.... KIM

Tuesday

Hi! I'm Larlyn your scribe for today's class... anyways..

Ms. Kozoriz go over the Vocabulary Review here's the answer....

1. Amplitude

2. Frequency

3. Interference

4. Wavelength

5. Standing Wave

6. Sound Level

7. Open-pipe resonator

8. Octave

9. Resonance

10. Consonance

11. Loudness

12. Dissonance

13. Timbre

14. Doopler Shift

15. Closed-pipe resonator

16. Fundamental

17. Beat

18. Pitch

19. Harmonics

20. Echoes

21. Decibels

And then she said that were having lab tomorrow. She read the yellow booklet we have, starts on page 6-9

Standing Wave Patterns in Longitudinal Waves

In our study of waves in an earlier module, we observed that a standing wave pattern is formed when reflected waves interfere with incidence waves to form a "standing wave" that appears to be standing in place. We learned that the frequency at which the standing wave exists is called the resonant frequency. Each resonance frequency is a whole-number multiple of the lowest resonance frequency called the fundamental frequency.

Sound waves are longitudinal waves, so to understand standing waves in sound let us look again at the Slinky. When the longitudinal waves reflect from a wall, the forward and backwad waves can produce a stading wave. As in a transeverse wave, there are nodes and atinodes. At the nodes the coils of the Slinky do not vibrate at all, that is they do not have any displacement. At the antinodes the coils vibrate with maximum amplitude. This is indicate by the dots with the arrows indicating back and forth movement. At an antinode, the coils have maximum displacement. The vibration occurs along the line of travel of the individual waves. In a standing wave, the molecules and atoms of the medium behave as the dots in the diagram below.

there's the diagram below your booklet.

next she read is about

Standing Waces: Tube open at Both Ends

Musical instruments in the wind family depend on longitudinal standing waves to produce sound. Wind instruments like the trumpet, flute, clarinet, pipe organ, and so are modified columns of air. Sound waves that originate at one end of the tube travel up and down each tube. This is possible because the sound waves reflect from both ends of the tube even though the ends are open. If the frequency of the tuning fork matches one of the natural frquencies of the air column, the downward and upward travelling waves combine to form a standing wave, and the sound of the tuning fork becaomes even louder.

The diagram below the page compare the standing waves in a Slinky on the left with the air pressure patterns on the right. The patterns on the right symbolize the amplitude of the vibrating air molecules at various locations. Where the pattern is widest, the amplitude of the vibration is the greatest. Whenever the pattern is narrow, there is no vibration. In both examples there is a displacement antinode at each end of the tube because air molecules there are free to move. As in the transverse wave the distance between two antinodes is one-half of a wavelength, so the length L of the tube must be an interger number n of half-wavelengths:

Some Formulas and Diagram

Read:

Standing Waves: Tube Open at One End

Measuring the Speed of Sound

Those two are our lab for tomorrow. She also gave us three sheets to work on:

Next Scribe...RAMINA!!!!^_^

Sound Stuff

Hello guys! Suzette here, scribing... duhh? Well anyway, today, what we did was go over the test that we wrote last week: Waves in Two Dimensions. I hope you guys are satisfied with your mark 'cause I am, haha. Then after that we went over the yellow booklet and learned more about sound waves... o.o

Here are some facts according to the booklet:

Natural Frequencies and Resonance

Natural Frequency is when an object is allowed to vibrate freely at a specific frequency.

- depends on the size, shape, and composition of the object.

Resonance is the condition in which force is applied to an oscillator at the point of maximum amplitude.

- is a matter of one object "getting in tune" with another object.

The Fundamental Frequency

* A standing wave can only be created in a medium of fixed length at certain frequencies. This wave can exist only at a resonant or natural frequency.

Vibrating objects that have only a single resonant frequency:
- tuning fork
- pendulum
- mass bouncing on a spring

Vibrating objects that have many resonant frequencies:
- rope
- stretched spring
- air in an air column (used in musical instruments)

Fundamental Frequency, f_o is the lowest frequency at which a system vibrates freely (standing waves).

Harmonics - the resonant frequencies of standing waves.

Fundamental frequency = first harmonic

Beats and Beat Frequency

So, what happens when sound waves have slightly different frequencies?

Well....

Let say you have two tuning forks with the frequency of 440 and 438. When you strike these forks, it creates a sound that rises and falls periodically so that it is faint, then loud, then faint again, then loud again, and you get the idea. These vibrations in loudness are known as beats. They are produced by the interference of sound waves with slightly different frequencies.

Beat frequency
- is the number of times that the loudness rises and falls every second.
- is the difference between two sound frequencies.
- based on the tuning forks above: 438 Hz - 440 Hz = 2 Hz
- 2 Hz is the beat frequency.

And that is all about the yellow booklet...

Moving on....

The next thing we did was watch a video about Beats of Sounds (it's the teacher guy who draws awesome straight lines) =)

The video is basically about you know, sounds.

The only thing I remembered is, when you have a water wave and then you add another wave, it produces NOTHING. And it's the same thing for the sound waves, they produce basically nothing. <<<<---- err... this, I'm not really sure. The video is so interesting I didn't even bother to write anything about it. However, if you know or have something to say, just say it so I can, maybe, fix it.

OKay, in addition...

the last thing we did was work on the Vocabulary Review sheet.

The End.

P.S. Sorry for the lack of effort (no illustrations at all).

---------

The NEXT SCRIBE is LARLYN!

Friday, October 3rd

Hey people, as you all know we had a test yesterday and i hope everyone did very well.

Today in class we did three labs with sound waves. The first one was using a ruler. In this lab you had to hold a ruler on the side of the desk and push it down and let it go so it makes a sound, producing sond waves. The second lab we did used a beaker of water and a plastic cylinder. In this lab you had to blow into the cylinder without water in it and listen to the sound, then you had to pour some water in and listen for a change in sound, finally you had to blow across the top of the tube while pouring water into the tube and explaine what you heard. Ther third lab was the most fun, in my opinion anyways. In this lab we got to use the tuning forks. We got to see how different size tuning forks with different frequencies made different sounds. The last thing we did in class, before we had the first of two fire drills in one day, was a vocabulary work sheet.

Well thats what we did in class today. Hope everyone has an amazing weekend.

Mondays scribe is going to be......umm lets see.. hmm... i pick.... Suzettes. :D Once again have a fabulous weekend!!!!!!!!!!!

Alex's Post, October 1, 2008

Hey everybody! It's Alex :) I've never done a blog before so sorry if this sucks. Anyway today in class we corrected the review and did a sheet on the overhead. I'll start with the review.

Here are my crappy examples of question 1:




Make sure your reflected wavefronts are the same length and distance from each other as the incident wavefronts!









Make an imaginary dot behind the barrier the same distance from the barrier as the original dot. From this dot draw you reflected wave rays.


Question 2) reflected wavelength= 1.6 cm

Question 3) a) n=o.75
b) Shallow Water: wavelength=2.07 cm
Deep Water: wavelength=2.75 cm
c) Angle of incidence= 32 degrees

Question 3 diagram)













Question 4) The wavelength of deep water is equal to 4.5 cm

Vs* lambda d= Vd* lambda s which equals lambda d= Vd* lambda s/Vs: this is the equation I used to find this.

With numbers it would look like:
lambda d= (1 cm/s) * (3 cm)/ (2/3 cm/s)


Question 5) The wavelength of 1.4 m would have the greatest diffraction because the longer the wavelength the greater the diffraction.

Question 6) The frequency of 200 Hz would have the greatest diffraction because the smaller the frequency the longer the wavelength and the longer the wavelength the greater the diffraction.

Question 7) Sorry I cannot draw this!
b) The perpendicular bisector indicates an area of constructive interference.
c) P2 is located on nodal line 2.
d) | PnS1-PnS2|=(n-1/2)*lambda: lambda equals 3 cm
e) 3.5 * 3 cm/ 1 lambda= 10.5 cm

Question 8) a) |PnS1- PnS2|=(n-1/2)*lambda: lambda equals 1.6 cm
b) f= V/ lambda
f= 3.44 Hz

So that is the review.

The over head sheet answers are:

1) The red arrows represent light rays.

2) The angle of incidence for light entering the glass is 60 degrees.

3) The angle of refraction for light entering the glass is 34.5 degrees.

4) The value of the angle of incidence leaving the glass is 34.5 degrees.

5) The value of the angle of refraction for light entering water is 40.5 degrees.

6) I would expect the glass to have a greater index of refraction because it's angle is closer to the normal which means it is denser which means it has a greater index of refraction.

7) n= Sin 60 degrees/ Sin 34.5 degrees= 1.5: index of refraction for glass

8) n= Sin 60 degrees/ Sin 40.5 degrees= 1.3: index of refraction for water

9) The light will travel faster through water.


So that is my post, good luck on the test tomorrow I hope everyone does well. And to everyone who's done a post already you should give yourself a pat on the back, scribing is hard work! I don't know who to pick for scribe, I don't really know how it works so I'll pick the wonderfully smart Katie N.
Bye! See everybody tomorrow :)