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2. Ophir Ortiz and Souheil Zekri Force and Motion Ophir Ortiz and Souheil Zekri Standard 1: 2. knows that waves travel at different speeds through different materials

3. Why are waves important? Waves are Waves transmit energy that topple buildings during earthquakes Our observations from earth to space are dependent on waves received by satellites Figure 1: Seismogram Figure 2: Satellite

4. Outline Definition of a wave Characteristics of waves Examples of waves Activity

5. What is a wave? Definition: A disturbance traveling through a medium by which energy is transferred from one particle of the medium to another without causing any permanent displacement of the medium itself In simpler terms, a wave may be described as a ripple or an undulation

6. Stadium wave http://www.colorado.edu/physics/2000/waves_particles/stadium_wave.html

7. Characteristics of Waves The characteristics of a waveform are: wavelength (period) wavelength (period) amplitude amplitude velocity velocity frequency frequency All periodic (repeating) waveforms have these common characteristics

8. Wavelength Wavelength is defined as the distance from one crest to the next crest. The wavelength of an ocean wave: several meters. The wavelength of the electromagnetic wave used in a microwave oven: ~ 1 centimeter.

9. Wavelength Applet

10. Amplitude The height of the wave is called its amplitude. Amplitude relates to loudness in sound (for a sound wave) and brightness in light (for an electromagnetic wave). A Amplitude

11. Velocity The velocity of the wave is the measurement of how fast a crest is moving from a fixed point. The speed of sound is about 1000 feet/second. The speed of light is 2.99 x 10 8 meters/second.

12. Frequency The frequency of waves is the rate the crests or peaks pass a given point. Cycles per second is also called Hertz. Frequency = Velocity / Wavelength

13. Classification of Waves Mechanical Electromagnetic Longitudinal Transverse Torsional Classification according to medium through which wave travels Classification according to wave orientation

14. Mechanical Waves Matter is the medium Sound is a mechanical wave

15. Electromagnetic Waves Electric and magnetic fields are the media Light is an electromagnetic wave

16. Longitudinal Waves A sound wave is a classic example of a longitudinal wave As a sound wave moves from the lips of a speaker to the ear of a listener, particles of air vibrate back and forth in the same direction and the opposite direction of energy transport http://www.glenbrook.k12.il.us/gbssci/phys/Class/sound/u11l1a.html

17. Transverse Waves Disturbance is perpendicular to the direction of propagation All electromagnetic waves are transverse. This includes light. : Two lines that meet at a right (90°) angle Perpendicular: Two lines that meet at a right (90°) angle

18. Transverse Waves Particles vibrate at right angles to the direction of the wave's velocity Example: waves along a string VELOCITY PARTICLE DISPLACEMENT http://online.cctt.org/physicslab/content/Phy1/lessonnotes/waves/lessonwaves.asp 90°

19. Torsional Waves waves which twist about a central axis

20. Tacoma Bridge

21. Sound Waves Sound is a waveform that travels through matter Sound will readily travel through many materials Speed of sound through air depends on: – –density of the material – –temperature MaterialVelocity m/s Air331 Water (50°C) 1540 Brass4490 Aluminum6400