1. 12.3 Properties of Waves pp. 452 -458 Mr. Richter

2. Agenda  Warm-Up  Review HW  Notes:  Types of Waves  Wave Speed  Waves and Energy

3. Objectives: We Will Be Able To…  Distinguish local particle vibrations from overall wave motion.  Differentiate between types of waves.  Apply the relationship among wave speed, frequency, and wavelength to solve problems.  Relate energy to amplitude.

4. Warm-Up:  How does sound travel from your mouth to a person’s ear?  Can you make sound travel faster?  Louder?

5. Types of Waves

6. Mechanical vs. Non-Mechanical Waves  Mechanical wave: a wave that propagates through a deformable, elastic medium  medium: the material through which a disturbance travels  Non-mechanical waves: do not require a medium through which to pass  X rays, magnetic waves, visible light, radio waves, etc.

7. Pulse vs. Periodic Waves  Periodic wave: whenever the source of the wave’s motion is a periodic motion (repeated), a periodic wave is produced.  Pulse wave: a wave consisting of a single traveling pulse.

8. Transverse and Longitudinal Waves

9. Transverse Waves  Particles of the medium move perpendicularly to the wave motion  For example: wave travels to the right as the particles of the Slinky move up and down. https://www.youtube.com/watch? v=UHcse1jJAto

10. Longitudinal Waves  when the particles of a medium vibrate parallel to the direction of the wave  also called a density wave or pressure wave https://www.youtube.com/watch ?v=aguCWnbRETU

11. Transverse and Longtudinal Waves  https://www.youtube.com/watch?v=Rbuhdo0AZDU

12. Wave Speed

13.  The speed of propagation of a mechanical wave depends on the medium through which the wave travels.  Some media are thicker or less flexible than others.  Think of sound traveling through water as opposed to traveling through air.  Speed of propagation of a mechanical wave is constant for any given medium.  Example: the speed of sound in air is always (roughly) 340 m/s.

14. Wave Speed  A wavelength is the displacement of a wave in one period of time. (How long is the wave for a complete cycle.)  If frequency is increased, wavelength must decrease.

15. Your Turn  The piano string tuned to middle C vibrates with a frequency of 264 Hz. Assuming the speed of sound in air is 343 m/s, find the wavelength of the sound waves produced by the string.  v = ƒ λ  343 m/s = 264 Hz * λ  λ =343/264 = 1.30 m

16. Waves and Energy

17.  Energy transfers from adjacent particles across the medium.  Waves transfer the motion of matter without transferring the matter itself.  This often makes waves a more efficient method to transfer energy.  The larger the amplitude, the greater the energy transferred.

18. Wave Energy Commercial  Wave Energy Wave Energy

19. Wrap-Up: Did we meet our objectives?  Distinguish local particle vibrations from overall wave motion.  Differentiate between types of waves.  Apply the relationship among wave speed, frequency, and wavelength to solve problems.  Relate energy to amplitude.

20. Homework  p. 470 #24-28, 35