1. SPH3U
THE DOPPLER EFFECT

2. Doppler effect
The Doppler effect occurs when a transmitter and receiver are in motion relative to one another: the received frequency is higher than the transmitted frequency if the two objects are approaching one another, and lower if they are moving apart.

3. http://faraday. physics. utoronto

5. Equation f2 = f1( v ) (v + vs) f2 = frequency observed (Hz)
f1 = frequency of source (Hz)
v = speed of sound (m/s)
vs = speed of source (m/s)
+ moving away moving towards

6. Example 1
The air temperature is 200C. A car horn has a frequency of 500Hz.
If the car travels away from you at 36 m/s, what is the apparent frequency?

7. Example 2
Repeat example 1 for the car travelling towards you.

8. Example 3
Rearrange the equation to solve for v:
f2 = (f1 v )
(v + vs)

9. Example 4 Rearrange the equation to solve for vs: f2 = f1( v )
(v - vs)

10. Supersonic Travel
Mach Number
= speed of object
speed of sound

11. Example 1 The air temperature is 200C. A plane travels at 1000 m/s.
What is the mach number?

12. Example 2 The air temperature is 150C. A jet is travelling at Mach 2.3
What speed is the jet travelling at?

13. Example 3 An object travels at 1044 m/s. The Mach number is 3.
What is the temperature?

14. As an airplane flies faster than the speed of sound, it "pushes" on the sound waves in front of it. But sound waves obey the speed limit--they can't travel faster than the speed of sound.
So the waves pile up against each other as they are created. These "piled up" waves are called shock waves. The greatest shock waves are at the tip and tail of the plane. This NASA photograph shows the shock waves created by a plane in flight (The "rings" in the photograph are camera artifacts and are not part of the shock waves

15. Every so often, just the right combination of conditions and events occur to create an unbelievable event -- in this case an F/A-18 Hornet passing through the sound barrier.
Not only were the water vapor, density and temperature just right, but there just happened to be a camera in the vicinity to capture the moment. Navy Ensign John Gay made this phenomenal photograph on July 7, 1999 while aboard the carrier USS Constallation as Navy Lt. Ron Candiloro flew by.

16. Breaking the Sound Barrier

17. You can learn a lot about sonic booms by looking at the wakes boats leave in the water.
If you toss a pebble in a pond, little waves will form in concentric circles and propagate away from the point of impact.
If a boat travels through the pond at 3 to 5 miles per hour, little waves will propagate in the same way both ahead of and behind the boat, and the boat will travel through them.

18. If a boat travels faster than the waves can propagate through water, then the waves "can't get out of the way" of the boat fast enough, and they form a wake.
A wake is a larger single wave. It is formed out of all the little waves that would have propagated ahead of the boat but could not.