Physics lecture: simple harmonic motion, waves and light

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1. Define sound waves
vibrations of longitudinal(repeating patterns of motion) sound waves or some other medium.
2. Sound waves in the air
pressure waves that move back and forth, producing a series of compression (high pressure) and rarefactions(low pressure) to produce a longitudinal sound wave.

vibrations of particles of a medium
3. Compression
regions of high air pressures
4. rarefaction
regions of low air pressure
5. wavelenghths
a disturbance of a medium that comes from a distance and travels in one complete wave cycle.
6. transverse wave
the measurement of one wave crest to the next adjacent wave crest. vibrations are perpendicular to the direction of motion.

looks like roller coaster track.

ex. water waves or sting waves
7. Light
• light is known as an electromagnetic wave
• light does not require a medium
• light is a transverse wave
8. longitudinal waves
repeating patterns of compression and rarefactions. vibrations are in the direction of motion.

looks like a spring

ex.

sound waves
9. ***speed of sound***

Pressure waves
• repeating patterns of high and low pressures
• (compresions and rarefactions)
10. High pressures in pressure waves
the arrival of a compression
11. low pressures in pressure waves
the arrival of a rarefaction.
12. ***frequency of sound***

Frequency
refers to how often the particles of the medium vibrate when a wave passes through.
13. Frequency of a wave
a number of complete back and forth vibrations of a particles through a medium per unit of time.

ex. F=1HZ/time
14. Harmonic motion
• the periodic motion of a motion that repeats itself
• A restoring force is responsible for the periodic motion
• Restoring force is proportional to the displacement
15. Hooke's law
For certain springs, the amount of force is directly proportional to the amount of stretch or compression (x); the constant of proportionality is known as the spring constant (k).

Fspring=-Kx

If a spring is not stretched or compressed, then there is no elastic potential energy stored in it.
16. wave properties
wave transport energy

• high waves----high energy
• low waves---low energy
17. intensity of a wave depends of the amplitude
• high intensity sound wave are loud
• high intensity light are bright
18. wave speed
speed of all waves depends on the frequency and wavelength

• v=speed
• ;= wavelength
• t=period
• f=frequency
19. sound waves
the propagation of longitudinal waves of high compressions and regions of rarefactions

ex. tuning forks form longitudinal waves
20. sound spectrum
sound spectrum has few frequencies and can be divided into three frequency regions.

• infrasonic f<20hz
• audible, 20hz<f<20khz
• ultrasonic, f>20khz
21. Longitudinal sound waves
sound is a longitudinal wave that is created by a vibrating object.  It can be created or transformed only in a medium and cannot exist in a vacuum
22. Condensation
a region of increased pressure (a compressed spring)
23. rarefaction
a region of released pressure.

the production of an inward motion when the air pressure is slightly less than normal
24. frequency of a sound wave
is the number of cycles per second that passes by a given location.
25. pure tone
a sound with a single frequency

ex. telephone push buttons
26. sound intensity
the amount of energy transported per second by a sound wave is called the power of the wave and is measured in SI units of joules per second or watts
27. sound intensity and distance
intensity decreases with distance from the source (I/r2)
28. sound intensity
the sound power P that passes perpendicularly through a surface divided by the area A of that surface.

I=P/A

SI units of sound intensity is power per unit area or W/m2
29. spherically uniform radiation
the sound source at the center of the sphere emits sound uniformly in all directions.

I=P/4TTr2
30. Decibel scale
a decibel is a unit in measuring the sound intensity level

greater intensities give rise to louder sounds,but doubling the intensity does not double the loudness.
31. doppler effect when sound approaches
the apparent change in frequency resulting from the relative motion of the source and the observer as sound approaches (higher frequency) or high wave lengths
32. doppler effect as sound leaves
the doppler effect for sound is recognized as a change in pitch when the sound is moving away (lower frequency) or low wavelength.
33. doppler effects in lights
the doppler effect for light leads to a change in color.
34. sources standing still
refers to an object with sound that is not moving will have the same condensation (loudness waves)
35. sources that are moving
refers to an object with sound is moving toward a person the wavelength will get smaller

wave length moving away from a person, the wavelength becomes larger apart

lambda '= lambda-VsT
36. sources moving toward a stationary observer
Fo=V/lamda'= v/lambda-VsT

fo=fs(1/1-vs/v)
37. source moving away from stationary observer
lambda'=lambda+VsT

Fo=V/lamda'= v/lambda-VsT

fo=fs(1/1+vs/v)
 Author: msmit458 ID: 211131 Card Set: Physics lecture: simple harmonic motion, waves and light Updated: 2013-05-16 19:26:40 Tags: simple harmonic motion waves light Folders: Description: simple harmonic motion, waves and light Show Answers: