Vibrating objects


This section is an extension of the applications expressed in What is Vibration? and Vibration and Sound.

Summary: Vibrating objects are everywhere around us but we rarely think about them like that. Sound is produced as a result from these vibrating objects through a process where an object vibrates the air around us which vibrates our eardrums and registers sound in our brains.

Below are some examples that demonstrate this process in action:

Drums


source: http://www.dosits.org/images/dosits/drumset.gif

Explanation: When a drum is hit, the head vibrates back and forth which causes an air displacement. From this displacement, air begins to vibrate and produce sound waves. These waves travel to our ear drums and often make a loud staccato sound. This staccato sound is produced by a short period but large amplitude sound wave.
Graphs of different sounds can be found here.


Soda Pop 'Hiss'

 
source:https://s-media-cache-ak0.pinimg.com/originals/cc/6e/b7/cc6eb7bc5952cab2077dccc655a4cd2f.jpg

Explanation: When you unscrew a cap off of a bottle of soda, the carbonated gas inside the bottle escapes through the small slit created by the gap between the lid and opening of the bottle. This happens because of a pressure difference between the inside of the bottle and the environment. When the gas rushes out, it causes the cap and sides of the bottle to vibrate quickly. This vibration is relatively unnoticeable to the bottle handler but it does effect the air around it, causing it too to vibrate at a quick pace. This quick vibration produces a tight oscillation pattern in the sounds waves which causes us to hear a high pitch 'hiss' noise. 


'Splash' Noises


source: http://kanon.parliran.ir/uploadeddata/previmages/gayeg_18013.gif

Explanation: A 'splash' is a noise that occurs as a result of a particle or object impacting a liquid and causing a portion of that liquid to be expelled upward and land at random times back into the liquid. Lets take the boat above as an example and break it down into it's different components.
The Boat:
The boat is traveling along the surface of the water with a certain velocity and acceleration provided by the force of the sail and engine. As the boat travels, you hear a slapping noise from the air rushing out from beneath the bottom of the boat
The Water Droplets:
You also hear the sounds of thousands of water droplets reentering the ocean. This sound is produced by water droplets creating air pockets as they impact the surface of the ocean. These air pockets travel to the surface of the ocean at which time they make a pop noise. Together, these noises create the 'splash' sound.
Quick Links

Vibration

Music



Tristan Van Cise
Physics 211
Fall 2016
David Newman
Website Project