ch25_egtk

=Chapter 25 Vibrations and Waves =

25.1 vibration of a pendulum
A pendulum is a string with a weighted object atached to the end of it. 
 * //__**Period (T)**__ is the amount of time that a pendulum to complete one vibration in a pendulum.//
 * //longer pendulums = longer period and shorter pendulums = shorter pendulums = shorter periods //

//25.2 Wave Discrition //
**//__Simple Harmonic Motion__//** is the back and forth motion of a pendulum.  Image from : [|https:/.../ electronics/signals.htm]  **//__Amplitude__//** is the distence between the mid point of the wave to the crest or to the trough. Frequency and period are inverses of each other:
 * If the pendulum is in simple harmonic motion then the movement is measured in a **//__Sine Curve.__//**
 * Sine Waves are waves that have two extreme points, the high point the __//**crest**//__ and the low point the __//**trough**//__.
 * //__Wavelength__//** is the distence between one crest to the next crest and/or one trough to the next trough.
 * //__Frequency__//** in a vibrating object is the number of vibrations for a certain amount of time.
 * Frequency is measured in **//__Hertz__//** (Hz)
 * An exaple of Hertz is if there is one vibration per second its 1 Hz, and 50 vibrations a second its 50Hz.
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Frequency = 1/Period
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Period = 1/Frequency

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.3 Wave Motion
<span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">Most information around us gets to us by some form of a wave. <span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">Waves do not transport matter they only transfer energy. Waves are carried by a disturance in a medium.
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Sound travels to our ears
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Light travels to our eyes
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Electromagnetic waves are picked up by signals that takes them to our radios.

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.4 Wave Speed
<span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">The speed of the wave depends on the meduim its moving through. <span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">Wave speed = frequency x wavelength (v= ƒλ)
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Wave speed in air is about 330 m/s to 350 m/s (Depending on Temperature).
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Wave speed in water is about 4x faster than through air.
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">v is the wave speed
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">ƒ is the frequency
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">λ is the wavelength.

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.5 Transverse Waves
<span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">A **//__Transverse Waves__//** is is a wave that travels right angles. This Image from: [|library.thinkquest.org/ 15433/unit5/5-1.htm]

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.6 Longitudinal Waves
<span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;"><span style="font-family: Verdana, Geneva, sans-serif;">A **//__Longitudinal Wave__//** is a wave where all the particals move along one direction (not at right angles). This image is from:[|library.thinkquest.org/ 15433/unit5/5-1.htm]

<span style="font-family: 'Lucida Console', Monaco, monospace;">A slinky is a good example of how to see a longitudinal wave, extend the slinky and push one end forward and watch waves move.

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.7 Interference
<span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">**//__Interference Pattern__//** is when 2 waves meet and either form a bigger or a smaller wave. For example, if you drop 2 rocks in the water the 2 waves can overlap creating an **//__interference pattern__//** <span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">__//**Destructive Wave.**//__ Image from: animals.howstuffworks.com Interference patterns are easiest to see in the water. image from: www.answers.com in the picture the places where you see the stripes are the places where the waves are constructivly interfering or are **//__In Phase__//** but where there is no waves right between the 2 waves is destructive interference or are **//__Out of Phase__//**
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">When 2 waves come together and the trough and crest of the 2 waves match up then the wave is a **//__Constructive Wave__//**
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">When 2 waves come together and the trough of one wave meets the crest of the other wave and vice versa then the wave is a

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.8 Standing Waves.
<span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">A **//__Standing Wave__//** is a wave that is formed when one end is fixed to a position and the other hand moves up and down, thus since the one end does not move then the wave is reflected back. image from: www.scienceforums.net
 * //__Nodes__//** are points in the standing wave that remain stationary depending on the speed of the wave.
 * //__Antinodes__//** are positions in the standing wave with the highes amplitude and is located halfway between the nodes.

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.9 The Doppler Effect.
<span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">**//__The Doppler Effect__//** is the change in frequency due to the motion of an object. <span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">If you are standing on the street and a screeming football fan in a car comes driving by with and airhorn blowing it out his window, you notice that the sound gets louder really quick and when he is passed you the sound slowly decreases, this is beacsue of the doppler effect.
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">The **//__Red Shift__//** in the doppler effect is the decrease in frequency and occurs when an object moves away.
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">The **//__Blue Shift__//** in the doppler effect occurs when an object is moving twards you and is the increase in frequency.

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.10 Bow Waves.
<span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">**//__Bow Waves__//** occur when an object in water moves faster than the water. <span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">this is known as a Bow Wave because you are moving faster than the water you are moving in. This happens not just in water but also when an aircraft breaks the sound barrier, when a jet goes faster than the speed of sound then there is a white cloud that surrounds the nose, this is also a bow wave. Image from : media-2.web.britannica.com
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">an exaple of this is swimming in the water, when you move forward you notice that there is a V-shaped wave given off when you move forward.

<span style="color: #000000; font-family: Verdana, Geneva, sans-serif;">25.11 Shock Waves.
<span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">**//__Shock waves__//** come from a supersonic aircraft generates a three-dimentional wave. <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;"> <span style="color: #7733eb; font-family: 'Lucida Console', Monaco, monospace;">Sonic Booms and Shock waves occur when an aircraft "Breaks the sound Barrier" or moves faster than the speed of sound. <span style="font-family: Verdana, Geneva, sans-serif;">
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Bow waves are 2 dimensional while a Shock wave is 3 dimensional.
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">When a Shockwave occurs there is a loud crackle that follows called a **//__Sonic Boom.__//**
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">Sonic booms cannot occur from a slower-than-sound, or subsonic aircraft because the tones are too slow to come off as one big sound but rather sounds more continuous.
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">image from [|www.chrisgood.com/ aircraft/]
 * <span style="color: #7733eb; font-family: Verdana, Geneva, sans-serif;">When an aircraft is flying faster than sound, people on the ground will see the aircraft and moments later will hear the sound of it passing by.