Doppler and Supersonic Travel The Doppler Effect Calculating

Doppler and Supersonic Travel • The Doppler Effect • Calculating Observed Frequency • The Doppler Shift • Redshift and Blueshift • Supersonic Travel • Mach Speed • Sonic Boom

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The Doppler Effect 1. Describe Sheldon's costume 2. Watch the video 3. Describe his costume in relation to the Doppler Effect

Doppler Effect • _____ • Examples: – moving cars and trains – rotating whistle – light waves In slideshow mode, click on the images above to see how your videos are embedded into the lesson.

The Doppler Effect • As the waves approach the observer, they become compressed (shorter wavelength) • ______ • As the waves move away from the observer, they move apart resulting in a lower frequency sound • This ………………. .

The Doppler Effect • The frequency of the sound source differs depending on the observer’s location. Car’s Motion • ______

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Check Your Understanding A car travelling at 100. 0 km/h sounds its horn as it approaches a hiker standing on the highway. If the car’s horn has a frequency of 440 Hz and the temperature of the air is 0°C, what is the frequency of the sound waves reaching the hiker a) as the car approaches? b) after it has passed the hiker?

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Application – The Doppler Shift • Recall: The Doppler Effect can be used for any wave (sound, light, etc. ) • _________ • Radar ………………

The Power of the Doppler Shift • It can also be used by astronomers to determine the speed and direction of moving objects in space – Redshift longer wavelengths as objects move away from you – _______

The Power of the Doppler Shift • It can also be used by astronomers to determine the speed and direction of moving objects in space – Redshift longer wavelengths as objects move away from you – ______

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Mach Speed • Mach Speed is simply a reference to the speed of sound in the particular medium. In a particular medium where the speed of sound is 332 m/s: – Mach 1 = 332 m/s (or 1 X the speed of sound) – Mach 2 = 664 m/s (or 2 X the speed of sound) – Mach 3 = 996 m/s (or 3 X the speed of sound) – Etc.

Supersonic Flight • The F-22 Raptor can reach speeds of Mach 2. 2 (2, 410 km/h, 1, 500 mph) • Upon reentry, some space shuttles can exceed Mach 25

Check Your Understanding At an altitude of 10 km, the speed of sound is approximately 1060 km/h. What is the Mach number of an aircraft flying at an altitude of 10 km with a speed of 1800 km/h?

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Supersonic Travel • THINK: Regarding the sound waves, what happens when the speed of the aircraft reaches the speed of the sound waves it produces? • What happens when ……………. . – For example, what happens if an airplane travels at approximately 332 m/s? What if it travels at 400 m/s?

Supersonic Travel • Aircrafts emit sound in all directions. Sound waves are compressed in front and spread out behind • At speeds equal to the speed of sound, the sound waves pile on top of each other and constructively interfere – the plane and sound are moving at the same speed • _____

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Supersonic Travel and Sonic Booms • Speeds greater than the speed of sound generate a noise cone of compressed sound waves – You wont be able to hear the aircraft until you are inside the cone – You hear the boom as it passes

Vapor Cone • A vapor cone can suddenly appear as the aircraft approaches the speed of sound • ______ • The cloud appears due to a sudden decrease in temperature around the …………. . • ______