Unit 5, Part 1: SOUND

1. Unit 5, Part 1:SOUND

2. WAVES SWBAT explain how waves are created and identify the different types of waves

3. What do you already know about sound and waves? (10 minutes total) • Create a CIRCLE thinking map • Write “Sound & Waves” in the center • Think about your point of views. Where have you learned about sound and waves before? • What words, images, or examples come to mind? • SHARE your thinking map with a partner. • DISCUSS as a class.

4. Sound Waves Video (5 minutes)

5. Key ideas in this PowerPoint will be in RED

6. Thinking about sound • Sound waves must go through a medium • The medium is made up particles • Mediums can be solid, liquid, or gas • Waves cause particles to vibrate and create sound • A wave occurs when there is a disturbance in a medium

7. Vibrations Sound is a form of energy that is produced by vibration (back-and-forth movement)

8. Vibration Examples When we talk, our vocal chords move. When we play the guitar, the string moves When you hit a drum, the drumhead moves When we talk, our vocal chords move. Each of these movement is a back-and-forth movement called a vibration Any more examples?

9. Properties of Sound Amplitude: how loud or soft a sound is. Measured by how much the medium is disturbed

10. Amplitude Determines Loudness

11. Amplitude Determines LoudnessHigher Amplitude = LouderLower Amplitude = SofterExample: you can beat a drum with different levels of intensity. The harder you beat the drum, the more vibrations, and thus a greater amplitude.

12. Loudness & Softness: The numbers represent “decibels,” or “db.” The human ear can hear from 0db’s to about 110db’s comfortably. 120db’s or more could result in ear damage.

13. Frequency of Waves Frequency is the number of waves produced in a given time

14. Types of waves • If a wave moves perpendicular to the motion of the particle, this is called a transverse wave

15. Types of waves • Longitudinal waves occur when a string is compressed and stretched. • The stretched and compressed regions travel along the spring • Sound waves are longitudinalbecause particles move parallel to wave motion

18. Longitudinal Waves (The Slinky Wave) • When the slinky is pressed together, we call this compression • When the slinky is stretched, we call this rarefaction

19. Parts of a wave • Crest • Trough • Resting Point • Wavelength (λ) • Amplitude

20. CREST THE CREST IS THE HIGHEST PART OF THE WAVE!

21. TROUGH THE TROUGH IS THE LOWEST PART OF THE WAVE

22. RESTING POINT Point “C” represents the dashed line. The dashed line is this wave’s resting point.

23. WAVE HEIGHT THE DISTANCE BETWEEN WAVE HEIGHT AND WAVE TROUGH

24. WAVE PERIOD THE TIME IT TAKES FOR ONE WAVE TO PASS

25. Example 1

26. Example 2: You can see this same thing in the ocean

27. Example 3

28. Measuring Waves • Frequency: the number of waves that pass a given point over a unit of time • Period: time required for one complete wavelength to pass a given point

29. The distance between points A and point B is the “wave length”

30. And remember, math and science are ALWAYS related…

31. frequency and period have an inverse relationship f = 1 or T = 1 T f Frequency (f) = hertz (H) Period (T) = seconds (s)

32. Wave Speed • We can determine wave speed using wavelength and frequency v = fλ V = wave speed f = frequency λ = wavelength

33. But, don’t worry about those calculations!

34. …YET!

35. Exit Ticket • Draw a wave and label the CREST, TROUGH, and RESTING point • In one sentence, explain how one would calculate a wave’s height • In one sentence, explain how one would calculate wave length • Sounds need to travel through a __________. • What is wave amplitude? • Write a 3-5 sentence summary about today’s lesson.