1. The Speed of Sound & Mach #
Textbook: 13.1, 13.2, 14.7
Homework: Worksheet
Discuss: is Sound a wave?
- Is it caused by vibrations? (Demo: Tuning fork and water)
- Does it transmit energy? (Demo: Decibel meter???)
- Travel around corners? (Demo: go outside)
- Pass through each other?
- Reflect
- Does it require a medium? (Demo: bell in a vacuum)
- Does it interfere? (Demo: Noise reduction headphones)
Discuss: What kind of wave is sound?

2. Sound as a Wave
Demo: Oscilloscope
Demo: LoggerPro frequency analysis

3. Sound as a Wave Sound is a longitudinal pressure wave
Pitch = Frequency
Volume = Amplitude
Quality is a measure of the complexity of the wave
Low quality = One frequency
High quality = Fundamental frequency with overtones
Demo: Oscilloscope
Demo: LoggerPro frequency analysis

4. The Speed of Sound
The speed of sound v (m/s) at sea level depends on the temperature T (C) of the air:
Pg. 449 #3
Discuss: Speed depends on medium and not on the source of the sound
Demo: Video of jet breaking the sound barrier

5. The Speed of Sound
The speed of sound v (m/s) at sea level depends on the temperature T (C) of the air:
Pg. 449 #3
Discuss: Speed depends on medium and not on the source of the sound
Demo: Video of jet breaking the sound barrier

7. Mach
Mach number is a way of measuring speed in multiples of vs. vo = speed of object, vs = speed of sound
Note: As vs changes so to will the Mach number
Ex. pg. 454 #1, 3

8. Mach
Mach number is a way of measuring speed in multiples of vs. vo = speed of object, vs = speed of sound
Mach # < 1: Subsonic
Mach # > 1: Supersonic
Mach # > 5: Hypersonic
Note: As vs changes so to will the Mach number
Ex. pg. 454 #1, 3

9. 1. What is the speed of a plane flying at Mach
a) 2.1 and 3°C? b) 0.4 and 35°C?
2. Convert the speeds in Question 1 to km/h.
3. Describe the process of a sound barrier forming. What happens when the object finally breaks through the sound barrier? Is a sonic boom necessarily going to occur?