1. Doppler Effect the change in wavelength due to motion of the source
Examples:
moving cars and trains
moving buzzer in a nerf ball
rotating whistle

2. Doppler Effect Doppler effect sounds like this:
Weeeeeeeeeeeeeee …Ohhhhhhhhhhhhhh
Doppler effect looks like this:
Frequency differs depending on the observer’s location.

3. Hearing the doppler effect
- denominator vmedium + vsource is used if source moving away from the observer
- use vmedium – vsource if source moving towards observer

4. Example 1. The Batmobile is approaching Batgirl at a speed of 140km/h while sounding its horn. Calculate the apparent frequency of the horn heard by Batgirl if the sound has a frequency of 500Hz. Assume a speed of sound of 344 m/s.

5. Example 2. (p461). If the sound of the horn has a frequency of 500 Hz, calc the apparent frequency heard by Robin if the Batmobile is travelling at 140km/h away from him. Assume speed of sound of 344m/s.

6. Mach (Measurement of Sound Speed)
A sonic boom occurs when an object goes faster than sound is able to travel. Water vapor appears as a suddenly condensed cloud as the jet creates a high density compression wave.
This is referred to as breaking the SOUND BARRIER.

7. Thinking: What is a sonic boom?

8. Thinking: Why does the sound wave get to us after the jet has passed us?
As a fast object approaches, observers on the ground are struck with incoming sound waves (like the wake of a motor boat).