If a tree falls in a forest and no one hears it, does the tree make a sound?
-
Upload
baldwin-johnson -
Category
Documents
-
view
221 -
download
1
Transcript of If a tree falls in a forest and no one hears it, does the tree make a sound?
![Page 1: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/1.jpg)
If a tree falls in a If a tree falls in a forest and no one forest and no one hears it, does the hears it, does the tree make a sound?tree make a sound?
![Page 2: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/2.jpg)
We have to know what We have to know what “sound”“sound” means. means.
• Let’s start at the beginning:– Think about a drum and how you make it make a sound.•You hit it with your hand or a stick/mallet.
– This causes the drum head to
_________________.4:12
![Page 3: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/3.jpg)
So what has to occur So what has to occur for a sound to form?for a sound to form?
•What is a vibration?–A rapid back and forth motion.
•Does everything that makes sound vibrate?–YES! Even the softest sounds and sounds humans can’t hear are caused by vibrations!
![Page 4: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/4.jpg)
What does a vibration do What does a vibration do to the air molecules that to the air molecules that surround the object making surround the object making
sound?sound?• It causes them to vibrate too!
– With each back and forth motion (vibration) of the drum head, a pulse is sent through the air molecules.Drum head
Drum head
![Page 5: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/5.jpg)
What type of wave is What type of wave is created?created?
• What happens to the air molecules when the “drum head” moves to the right?
• To the left?
![Page 6: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/6.jpg)
Parts of a Parts of a Longitudinal Wave:Longitudinal Wave:
RarefactionRarefaction
CompressionCompression
![Page 7: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/7.jpg)
Does a sound wave travel Does a sound wave travel in a straight line?in a straight line?
• Think about our classroom:– If I speak directly to the back wall can only the people in that line hear me?
• Sound waves travel out from the source in all directions!
![Page 8: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/8.jpg)
The Speed of SoundThe Speed of Sound• Let’s say you’re at an orchestra concert:– Do you hear the violins before you hear the cellos?
– The timpani before the French horns?
![Page 9: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/9.jpg)
That’s because the sounds That’s because the sounds travel through the air at travel through the air at
the same speed.the same speed.• At room temperature (about 20*C), sound travels through air at about 343 meters per second!– That’s faster than most jet planes travel!
![Page 10: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/10.jpg)
BUT…BUT…• Sound doesn’t always travel at that speed.
• The speed of sound depends on factors such as– Temperature– Density
![Page 11: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/11.jpg)
What is temperature?What is temperature?
• Not just how hot or Not just how hot or cold something is…cold something is…
• Think about the Think about the molecules in a molecules in a substance:substance:– If a substance is hot, If a substance is hot, how do the molecules how do the molecules behave?behave?
– Cold?Cold?
![Page 12: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/12.jpg)
SO…SO…• If a sound wave is moving through a hot substance, will it be easier or harder for the wave to travel?
• Why?– If the particles are already moving around rapidly, bumping into each other, then they can transfer the sound’s energy easier!
![Page 13: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/13.jpg)
What is Density?What is Density?• The number of particles in a certain amount of a substance.
• Put the following in order from most to least dense:
Liquid
Gas
Solid
![Page 14: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/14.jpg)
Think back to Think back to how sound how sound
waves move…waves move…• Which would transfer sound more quickly?– Solid liquid, or gas?
• Why?– The sound wave doesn’t have as far to travel between molecules in a more dense substance!
![Page 15: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/15.jpg)
The Coat Hanger Lab:The Coat Hanger Lab:• Explain why you could hear the coat hanger better with your fingers in your ears:– The sound traveled through a solid (the hanger, string, your fingers) all the way to your ears rather than through a gas (the air)!
• Use what you’ve learned:
• What are some things we could do to make it sound even better?
![Page 16: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/16.jpg)
Properties of SoundProperties of Sound
•LoudnessLoudness•PitchPitch
![Page 17: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/17.jpg)
LoudnessLoudness• When you yell, do you use more energy than when you speak softly?
• That’s what loudness is!– Your perception of the energy of a sound.
![Page 18: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/18.jpg)
PitchPitch• What kind of sound do you hear when a bass drum booms?
• When a seagull screeches?
•The highness or lowness of a sound is pitch.
![Page 19: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/19.jpg)
What determines pitch?What determines pitch?
• Think back to the tuning fork lab:– How did the frequency of the tuning fork (Hz) relate to the pitch?•The higher the frequency, the higher the pitch.
•The lower the frequency, the lower the pitch.
![Page 20: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/20.jpg)
So frequency So frequency determines pitch!determines pitch!
• What is frequency?– The number of waves that pass a point in a certain amount of time.
• If more waves pass a point in a certain amount of time, the pitch will be ________________.
![Page 21: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/21.jpg)
Which has a higher Which has a higher pitch?pitch?
![Page 22: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/22.jpg)
This also relates to the This also relates to the vibrations given off by vibrations given off by
an object.an object.
![Page 23: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/23.jpg)
So the faster an object So the faster an object vibrates, the higher the vibrates, the higher the pitch and vice versa.pitch and vice versa.
• Describe the frequency and vibrations given off by the following:
![Page 24: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/24.jpg)
Glass Harp/HarmonicaGlass Harp/Harmonica• What does the water do as you run your finger around the rim?
• What makes the sound you hear?
• CHECK IT OUT!– http://www.youtube.com/watch?v=M8E-XKrbWw4
– http://www.youtube.com/watch?v=R-CWCEJPq4w
![Page 25: If a tree falls in a forest and no one hears it, does the tree make a sound?](https://reader030.fdocuments.in/reader030/viewer/2022032706/56649dfe5503460f94ae6b99/html5/thumbnails/25.jpg)
SO…SO…•If a tree falls in a If a tree falls in a forest and no one forest and no one hears it, does the hears it, does the tree make a sound?tree make a sound?