Chapter 1: Waves

1. Chapter 1: Waves Waves interact and transfer energy in predictable ways

2. 1.1 Waves transfer energy How forces cause waves How waves transfer energy How waves are classified

3. wave • a disturbance that transfers energy from one place to another • waves transfer energy over distance without moving matter the entire distance

4. Where Do Waves Get Energy? • Vibration-Any movement that follows the same path repeatedly. An object that is vibrating is moving. A force causes the vibration. • An object that is moving has energy. • A vibrating object gives off some of its energy to nearby particles. This movement of energy from a vibrating source outward is a wave. • Waves get their energy from a vibration.

5. Vibrations • Example: The top of a drum vibrates after it is struck by a drum stick. It moves up and down several times creating sound. • Example: Your ear drum vibrates in response to sound which enables you to hear.

6. medium • any substance that a wave moves through • ex. water, the ground, a rope, air

7. Waves Through Matter and Space • Medium-Matter or substance through which a wave is transmitted. • Water is a medium for ocean waves. • Air is a medium for sound waves. • All phases of matter solids, fluids, plasmas, can act as a medium.

8. mechanical waves • any wave that transfers energy through matter (must have matter to work) wavelength

9. transverse waves • the direction in which the wave travels is perpendicular to the direction of the disturbance

10. longitudinal wave • the wave travels in the same direction as the disturbance

11. 1.2 Waves have measurable properties how amplitude, wavelength and frequency are measured how to find a wave’s speed

12. Amplitude • the distance between a line through the middle of a wave and a crest or trough. • see p. 17

13. wavelength • the distance from crest to crest • or trough to trough

14. frequency • the number of wavelengths passing a fixed point in a certain amount of time (usually a second) • Waves / second (hertz)

15. Wave speed • speed = wavelength x frequency • S = λ ∙ f

17. 5 QQ • Draw a transverse wave. • Label the wavelength. • Label the amplitude. • Draw a low amplitude transverse wave and a high frequency transverse wave. • Draw a longitudinal wave, label the rarefactions.

19. 1.3 Waves behave in predictable ways How waves change as they encounter a barrier What happens when waves enter a new medium How waves interact with other waves

20. reflection • the bouncing back of a wave after it strikes a barrier

21. refraction • the bending of a wave as it enters a new medium • occurs because waves travel at different speeds in different mediums

22. diffraction • the spreading out of waves through an opening or around an obstacle

23. interference • waves interact with other waves • they can add energy to, or take energy away from each other • the meeting and combining of waves

24. Suppose that you create a wave by moving a rope up and down. What will happen if you increase the energy you put into the rope? What will happen if you increase the speed of the motion?amplitude, frequency, wavelength

25. wavelength • frequency • amplitude • reflection • refraction • diffraction • medium • disturbance • force • hertz • mechanical wave • wave • transverse wave • longitudinal wave • interference • crest • trough • vibration • constructive interference • destructive interference • wave speed • compression • rarefaction • waves / second