1. Doppler Effect and Sonic Booms
Physics
Tiffany Rhodes

2. STATIONARY SOURCE A Bug Jiggling in Still Water = Fixed Position
Same Speed, wavelength
and frequency in all
directions
A and B experience exact
same frequency!!
In Sound, both hear
the same Pitch, the actual pitch!

3. Stationary Source

4. MOVING SOURCE Bug Swimming at same speed
A and B experience different frequency!
A = Lower Frequency
B = Higher Frequency
Moving away = low pitch
Moving Toward = high Pitch

5. Moving Source

6. DOPPLER EFFECT http://www.youtube.com/watch?v=imoxDcn2Sgo

7. Doppler Effect Explained
Science is fun explanation of the doppler effect
Big bang theory clip

8. Doppler Effect Explained with MATH
F’ = perceived frequency
Fo = actual frequency
V = speed of sound
Vs = Speed of source
+ use when source is moving away from observer
- use when source is moving toward observer

10. SONIC BOOMS Break through the ‘pile up’ of waves
Overlapping wave crests disrupt the flow of air over the wings, making it harder to control the craft.

11. Moving Same Speed as Sound
Now the source is moving at the speed of sound in the medium
(vs = v, or Mach 1).

12. Who was the person to break the sound barrier?
What was the type of plane that he used to break the sound barrier?

13. Chuck Yeager was the first person to break the sound barrier when he flew faster than the speed of sound in the X-1 rocket-powered aircraft on October 14, 1947
Fastest Aircrafts

14. Moving Faster than Speed of Sound Supersonic
It is this intense pressure front on the Mach cone that causes the shock wave known as a sonic boom as a supersonic aircraft passes overhead

15. Mach supersonic

16. Shock Wave – increase in pressure

17. Shock Waves
Subsonic – sound waves reaching our ears are perceived as one continuous tone
Supersonic – sound waves overlap to reach listener in a single burst
- increase in pressure is like the sudden expansion of air produced from an explosion

19. Supersonic on the Ground

21. Airplane Facts
The Lockheed SR-71 Blackbird is, to date, the fastest airplane ever to streak across the sky, even though it's more than 30 years old. Capable of speeds over 2200 mph -- that's more than 3X the speed of sound -- the SR-71 can fly at altitudes above 80,000 ft.

22. Sonic Boom (Breaking the Sound Barrier)
Ted Ed Talk on Sonic booms

23. Sonic Booms Reviewed

24. Make sure you are keeping up with your work
Make sure you are keeping up with your work. Finish Worksheets Pg 353 top#1-2, bottom of page #1-2 pg 355 #1-3 Pg 389 #1-3 Pg 390 #1-2 Read Pages Pg # 48,58,59

25. Physics CP1 Tiffany Rhodes Chapter 12
Mach Number
Physics CP1
Tiffany Rhodes
Chapter 12

26. Mach Number What do you already know about Mach Number?
Related to sound??
Related to air planes??

27. Mach Number Relates speed of object with speed of sound
Usually used with aircrafts since they are our fastest means of travel
Mach Number = Speed of Object/ Speed of sound
Speed of object and sound have to have same units. They cancel out…
Mach Number has No units!

28. What do you know about an airplane that travels at mach 1?
It is traveling at the same speed of sound
What do you know about an airplane that travels at mach 2?
It is traveling double the speed of sound

31. II. Wave Equation
Sound is a wave so therefore the wave equation still applies.
Speed of the wave = wavelength * frequency
V =  * f

32. Questions
Mach Number problems?
Wave Equation problems?

33. A rocket is traveling at 8643.6 km/hr.
Warm Up
A rocket is traveling at km/hr.
If the air temperature is 20ºC, what is the rocket’s Mach Number?

34. Answer Speed of object = 8643.6 km/h Speed of sound = 332 + 0.6* Temp
= (20)
= 344 m/s
Convert to km/h
344m 1 km sec
1 sec 1000m 1h
= km/h
Mach # = Speed of Object/Speed of sound
= / = 7