 Waves are oscillations and they transport energy.  Medium: The matter through which a wave travels  2 Subsets of Waves: Mechanical  waves that require a medium to travel through  (sound, water, earthquakes) Electromagnetic  waves that do not require a medium to travel  (light)

 Most waves are caused by vibrating particles Energy is transported, but the particle simply vibrate in one small area  Waves are classified according to the direction in which the particles in the medium move as the wave passes  2 Types: Transverse Longitudinal

 Transverse Wave Particle motion is perpendicular to the direction of wave motion  Examples water waves light waves earthquake S-waves

Wavelength = length or size of one full oscillation Amplitude = from sitting wave to a crest Crest = highest point in the wave Trough = Lowest point in the wave Resting State = The very middle, as if there were no waves

Remember that the molecules are simply vibrating up and down, NOT moving from one end to the other

 Longitudinal wave Particle motion is parallel to the direction of wave motion  Examples: sound waves earthquake P-waves

Compressions – area where the medium is pushed close together Rarefaction – area where the medium is spread further apart

Remember that the molecules are simply vibrating left and right, NOT moving from one end to the other

 wavelength (meters (m)) length or size of one oscillation of a wave v = velocity (m/s) how fast the wave is traveling f = frequency (Hertz (Hz)) How many full wavelengths per second occur

 Measure from any identical two successive points  Symbol for wavelength is lambda(  and is measured in meters (m)  Oscillation = 1 complete wave cycle  There are 4 complete oscillation depicted here (m)

 The distance from one crest to the next crest, or from one trough to the next trough.  It can be between any two successive points actually!  Can exist in a longitudinal wave from one compression to the next compression.  We will only concentrate on TRANSVERSE waves.

 Frequency = number of WAVES passing a stationary point per second  Symbol is f  Measured in Hertz (Hz)

= v/f  wavelength (meters (m)) length or size of one oscillation of a wave v = velocity (m/s) how fast the wave is traveling f = frequency (Hertz (Hz)) How many full wavelengths per second occur

= v/f  The string of a piano that produces the note middle C vibrates with a frequency of 262Hz. If the sound waves produced by this string have a wavelength in air of 1.3m, what is the speed of the sound waves? = v/f 1.3m = v / 262Hz 340.6m/s = v

 Remember, a wave is just transporting energy!  The 2 ways to increase the energy a wave carries. 1) Increase the amplitude of a wave 2) Increase the frequency of a wave  (done by decreasing wavelength)

 a-string/wave-on-a-string_en.html a-string/wave-on-a-string_en.html

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 Change in frequency of a wave due to relative motion between source and observer. A sound wave frequency change is noticed as a change in pitch.  Basically, as an object making noise moves closer to you, the pitch of the noise will increase Because the sound waves are compressed upon each other  As an object making noise moves away from you, the pitch of the noise will decrease Because the sound waves are further away from each other

 Sound normally occurs like this from a stationary object  With a moving object, the sound being produced is not moving to each side evenly.

 Sound normally occurs like this from a stationary object

 Now the object starts slowly moving to the right

 The object is now traveling right at the speed of sound (340 m/s or 767 mi/hr)

 The object is now traveling right faster than the speed of sound.

 Flash/ClassMechanics/Doppler/DopplerEffect.ht ml Flash/ClassMechanics/Doppler/DopplerEffect.ht ml  ore_stuff/flashlets/doppler.htm ore_stuff/flashlets/doppler.htm