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).

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The NEXT SCRIBE is LARLYN!