1. The Doppler Effect ► Time to demonstrate ► Please cooperate ► See you downstairs, outside by the main entrance in three minutes ► Any questions??? ► Let’s go!

2. Let’s think about what your heard ► Did you hear the Doppler effect? ► Do you understand the Doppler effect? ► Do you know what it means??? ► Let’s ask “Sheldon”… ► Video please ► Now let’s calculate the Doppler effect…

3. Doppler Effect ► When the source of sound approaches an observer, the observed frequency of the sound increases; when the source moves away from the observer, the observed frequency of the sound decreases. ► Diagrams of the Doppler Effect ( next slide)

4. Okay, who put this in here!!!

5. Diagram of the Doppler Effect

6. Formula for the Doppler Effect ► f obs = v sound f source ► v sound + v source ► Where: f obs = frequency observed ( Hz) f source = frequency of source ( Hz) f source = frequency of source ( Hz) v sound = velocity of sound ( m/s) v sound = velocity of sound ( m/s) - if the source is moving toward the observer + if the source is moving away from the observer + if the source is moving away from the observer

7. Problem #1: Car travelling ► A car travelling at 100 km/h sounds it horn as it approaches Joseph standing on the highway. ► STOP- Okay Joseph, why are you standing on the highway???? ► You are going to get hit!!! ► Get off the highway! ► If the car’s horn has a frequency of 440 Hz and the temperature of the air is 0 0 C, what is the frequency of the sound waves reaching Joseph ► a) as the car approaches Joseph? ► b) after it has passed Joseph? ► Answer: ► a) f obs = 480 Hz ► b) f obs = 406 Hz

8. Your Turn… ► MHR pg. 396 #11-15 ► Doppler Effect: Worksheet