Heeey! So I figured I should do this first before I lose focus with my other homework (besides I need a small break inbetween English and Bio -_-"). Okay so for those of you who lost track because of the small break inbetween posts that happened recently, this post is for Monday, October 6.
We started the class with Ms.Kozoriz handing back our tests and going over the answers, checking if anyone had any questions about it. For those of you who did well, congratulations and keep it up. For those who didn't do as well, you'll get it next time! (:
I would put up the answers for the test, but it wouldn't make much sense if you did miss today because you won't have your test in front of you. I would suggest getting your test from Ms. K when you can and then just compare your answers with someone in class if you have any questions about it. Between everyone in the class, all the right answers are there. From what I've seen (which is mostly just the people who sit in the front corner with me), a lot of people messed up on the fish question (the one that asked "where is the fish?"), but then there are those people who got it.
After getting our tests back, we read from the bottom of page 4 (Natural Frequencies and Resonance) to the middle of page 6 (Beats and Beat Frequency) in the yellow "Sound" booklet.
I'll quickly go over each concept as best as I can.
Natural Frequencies and Resonance
The natural frequency of an object (example used in the boolet is a pendulum) is the specific frequency at which it freely vibrates. It depends on some sort of length.
ex. shorter pendulum = higher frequency
longer pendulum = lower frequency
Any object that vibrates at it's own natural frequency will do so with the largest possible amplitude it can achieve. This is the frequency where it is easiest for a vibration to happen (also called the resonant frequency). With this, a small, repeated force can create a very large vibration.
ex. (in the booklet) "If a car is stuck in snow, it can be rocked back and forth at the same resonant frequency of the system. This motion builds up the amplitude, helping to get the car stuck in the snow."
If you picture that in your head, it will make resonant frequency and resonance easy to understand.
The Fundamental Frequency
A resonant/natural frequency is the frequency at which a standing wave is able to exist. Some objects, like a tuning fork or a pendulum, have only one resonant frequency. Other objects, like a rope or a stretched spring have many different resonant frequencies. In these cases, all of these resonance frequencies are all a whole-number multiple of the lowest resonant frequency. That frequency is called the fundamental frequency or f0.
So this picture represents the sound waves of two tuning forks hit out of phase (or is it "fase"?). In case you forgot, these were drawn as longitudinal waves because (for me) it's a little easier to see how this works this way. The green boxes represent destructive interference. Here the sound intensity (volume) drops. If the waves that are superimposing have the same amplitude, the sound intensity drops to zero. The purple boxes represent constructive interference. Here, the sound intenisty rises making a louder sound. The periodic variations in the loudness of sound are called beats. They are the result of when sound waves with slightly different frequencies interfere with each other (like in my badly drawn picture). Beat frequency is the number of times loudness rises and falls in one second. To calculate it, you just take the differences of the two sound frequencies.
ex. If sound wave one had a frequency of 440 Hz and wave two had a frequency of 438 Hz, the beat frequency would be 440Hz-438Hz or 2Hz.
So that covers the booklet. Next we worked on a vocabulary review sheet for chapter 15 in the green textbooks in class. For those of you who didn't show up today, here are the questions:
1) The maximum displacement from rest position is the ___of a wave.
2) The number of complete vibrations per second measured at a fixed location is the __ of a wave.
3) The result of superposition of two or more waves is _____.
4) The shortest distance between points where the wave pattern repeats itself is the ____ of the wave.
5) If the period of a wave is equal to the amount of time it takes for the wave to travel to a fixed point and back, the waves reinforce each other and a(n) ____ is produced.
6) Sound pressure is the ____.
7) A resonanting tube that has both ends open is a(n) ______.
8)The difference bewteen two frequencies that have a ratio of 2:1 is a(n)_______.
9) Increasing the amplitude of a vibration by repeatedly applying a small external force at the same natural frequency is _____>
10) A complex wave that has a pleasant sound is a(n) ______.
11) The amplitude of a wave causes the ____ of the sound that is heard.
12) A complex wave that has an unpleasant sound is a(n) _______.
13) Sound quality is ____.
14) The frequency of a sound seems to be higher as it approaches a listener and lower as it moves away from a listener because of the _______.
15) A resonating tube with one end closed is a(n)_____.
16) In a pipe resonator, the lowest resonant frequency is the ______.
17) The oscillation in the amplitude caused when waves of slightly different frequencies are added is a(n) __________.
18) The frequency of a wave causes the ____ of the sound that is heard.
19) In a pipe resonator, multiples of the fundamental frequency are the __________.
20) Reflected sound waves are______.
21) The unit of sound level is the _______.
Word Bank
amplitude, beat, closed-pipe resonator, consonance, decibel, dissonance, Doppler Shift, echoes, frequency, fundamental, harmonics, interference, loudness, octave, open-pipe resonator, pitch, resonance, sound level, standing wave, timbre, wavelength
So after this, we watched more of that guy who looks like Chuck Norris from before (if you don't know who this is, "check your neighbour" xD). This time, he talked about the three concepts that we read about in the yellow booklet. Visual aids always help a lot. Too bad I can't find the whole video so I can post it here. However, I did find these:
We started the class with Ms.Kozoriz handing back our tests and going over the answers, checking if anyone had any questions about it. For those of you who did well, congratulations and keep it up. For those who didn't do as well, you'll get it next time! (:
I would put up the answers for the test, but it wouldn't make much sense if you did miss today because you won't have your test in front of you. I would suggest getting your test from Ms. K when you can and then just compare your answers with someone in class if you have any questions about it. Between everyone in the class, all the right answers are there. From what I've seen (which is mostly just the people who sit in the front corner with me), a lot of people messed up on the fish question (the one that asked "where is the fish?"), but then there are those people who got it.
After getting our tests back, we read from the bottom of page 4 (Natural Frequencies and Resonance) to the middle of page 6 (Beats and Beat Frequency) in the yellow "Sound" booklet.
I'll quickly go over each concept as best as I can.
Natural Frequencies and Resonance
The natural frequency of an object (example used in the boolet is a pendulum) is the specific frequency at which it freely vibrates. It depends on some sort of length.
ex. shorter pendulum = higher frequency
longer pendulum = lower frequency
Any object that vibrates at it's own natural frequency will do so with the largest possible amplitude it can achieve. This is the frequency where it is easiest for a vibration to happen (also called the resonant frequency). With this, a small, repeated force can create a very large vibration.
ex. (in the booklet) "If a car is stuck in snow, it can be rocked back and forth at the same resonant frequency of the system. This motion builds up the amplitude, helping to get the car stuck in the snow."
If you picture that in your head, it will make resonant frequency and resonance easy to understand.
The Fundamental Frequency
A resonant/natural frequency is the frequency at which a standing wave is able to exist. Some objects, like a tuning fork or a pendulum, have only one resonant frequency. Other objects, like a rope or a stretched spring have many different resonant frequencies. In these cases, all of these resonance frequencies are all a whole-number multiple of the lowest resonant frequency. That frequency is called the fundamental frequency or f0.
The resonant frequencies of the standing waves are also known as harmonics. This is because in music, they harmonize with each other. The fundamental frequency is called the first harmonic. In the fundamental frequency, the distance between the two end points is equal to one half of a wavelength creating only one loop and one antinode.
*Image from :http://www.miqel.com/images_1/jazz_music_heart/harmonics.jpg
Beats and Beat Frequency
This section has a lot to do with constructive and destructive interference. To help you understand this, I drew a diagram (because I couldn't scan the picture xD). Please excuse my horrible paint skills.
So this picture represents the sound waves of two tuning forks hit out of phase (or is it "fase"?). In case you forgot, these were drawn as longitudinal waves because (for me) it's a little easier to see how this works this way. The green boxes represent destructive interference. Here the sound intensity (volume) drops. If the waves that are superimposing have the same amplitude, the sound intensity drops to zero. The purple boxes represent constructive interference. Here, the sound intenisty rises making a louder sound. The periodic variations in the loudness of sound are called beats. They are the result of when sound waves with slightly different frequencies interfere with each other (like in my badly drawn picture). Beat frequency is the number of times loudness rises and falls in one second. To calculate it, you just take the differences of the two sound frequencies.
ex. If sound wave one had a frequency of 440 Hz and wave two had a frequency of 438 Hz, the beat frequency would be 440Hz-438Hz or 2Hz.
So that covers the booklet. Next we worked on a vocabulary review sheet for chapter 15 in the green textbooks in class. For those of you who didn't show up today, here are the questions:
1) The maximum displacement from rest position is the ___of a wave.
2) The number of complete vibrations per second measured at a fixed location is the __ of a wave.
3) The result of superposition of two or more waves is _____.
4) The shortest distance between points where the wave pattern repeats itself is the ____ of the wave.
5) If the period of a wave is equal to the amount of time it takes for the wave to travel to a fixed point and back, the waves reinforce each other and a(n) ____ is produced.
6) Sound pressure is the ____.
7) A resonanting tube that has both ends open is a(n) ______.
8)The difference bewteen two frequencies that have a ratio of 2:1 is a(n)_______.
9) Increasing the amplitude of a vibration by repeatedly applying a small external force at the same natural frequency is _____>
10) A complex wave that has a pleasant sound is a(n) ______.
11) The amplitude of a wave causes the ____ of the sound that is heard.
12) A complex wave that has an unpleasant sound is a(n) _______.
13) Sound quality is ____.
14) The frequency of a sound seems to be higher as it approaches a listener and lower as it moves away from a listener because of the _______.
15) A resonating tube with one end closed is a(n)_____.
16) In a pipe resonator, the lowest resonant frequency is the ______.
17) The oscillation in the amplitude caused when waves of slightly different frequencies are added is a(n) __________.
18) The frequency of a wave causes the ____ of the sound that is heard.
19) In a pipe resonator, multiples of the fundamental frequency are the __________.
20) Reflected sound waves are______.
21) The unit of sound level is the _______.
Word Bank
amplitude, beat, closed-pipe resonator, consonance, decibel, dissonance, Doppler Shift, echoes, frequency, fundamental, harmonics, interference, loudness, octave, open-pipe resonator, pitch, resonance, sound level, standing wave, timbre, wavelength
So after this, we watched more of that guy who looks like Chuck Norris from before (if you don't know who this is, "check your neighbour" xD). This time, he talked about the three concepts that we read about in the yellow booklet. Visual aids always help a lot. Too bad I can't find the whole video so I can post it here. However, I did find these:
Resonance
Interference/beats
And that ends this lengthy post. Sorry if you had to read all of this, but hey, at least you learned something, hopefully. -_-"
Oh right! I got really bored so I had fun choosing the next scribe! The next scribe is:
Congratulations JohnI! You are the next scribe!
5 comments:
OMG he's on youtube!? XD awesome.
YESH, that's an awesome way to pick the next scribe [cuz it's not me ^-^] XD Haha. I can't explain anything like that :(
what's this guy's name again? haha
you know who i really miss? Bill Nye.. that studmuffin knows his stuff
lmao "studmuffin"
Excellent description of what happened in class today. Great job!
I guess you could practice working on your paint skills :)
this post will be one of the very few reasons to why i'll past physics. LOL
Post a Comment