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SPEED OF SOUND. Total Recall. Remember, V = λ f Velocity of the Wave = wavelength x frequency. Speed of Sound. The speed of sound varies Changes with - medium (solid, liquid, gas) - temperature. Where do you think sound moves the fastest???
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Total Recall • Remember, V = λf Velocity of the Wave = wavelength x frequency
Speed of Sound • The speed of sound varies Changes with - medium (solid, liquid, gas) - temperature
Where do you think sound moves the fastest??? Fastest in Solids, then liquids, then gas More molecules, less space carries vibration further
It’s Gettin’ Hot in Here…. • What temperatures do you think sound moves faster? Hotter temperatures More molecules already vibrating, easier to carry vibration
Its time for the Calculator Vsound = (331 + .6T) T = temperature in 0C 0C = 5/9 (0F-32)
I Accept • The accepted value for the speed of sound at room temperature at sea level is vsound = 343 m/s (770 mph)
Go Speed Racer • 1 times the speed of sound = Mach 1 Mach # = # x speed of sound So Mach 1 = 343 m/s
Bustin’ Out • Objects are able to travel faster than the speed of sound • This can be observed
Not a Cloud in the Sky • Pictures like these are often said to show a jet ‘busting’ through the sound barrier • This is WRONG!!! • Most times these planes are Transonic, traveling right below the speed of sound, near Mach .9 to Mach .99 • It’s simply water vapor condensing around low pressure areas of the air stream
Prandtl-Glauert cloud • What you see
As Fast as You can • Fastest jet aircraft – SR-71 Blackbird Mach 3.3 • Fastest rocket aircraft – X-15 Mach 6.7 • Fastest air vehicle (scram jet) – X-43 Mach 9.8 (not piloted)
Ready or Not…. • As an airplane moves, it pushes air molecules out of its way, continuously creating waves of compressed and uncompressed air.
Here comes the BOOM!!! • 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 and the "piled up" waves are called shock waves. Note the Rings are simply from the camera used.
What you hear as the ‘boom’ is caused by the sudden dramatic change in pressure that hits your eardrum. • You should actually hear two booms, one from the front of the jet and one from the back of the jet, as two cones are created at these points • Since most aircraft are small, it’s hard to hear both because they happen so quickly • On the Space shuttle, since it is 122 ft long, there is enough time to hear both (about .5 seconds)
Bull WHIP • The tip of a bull whip can be made to travel at supersonic speed • When you crack the whip, you are hearing a minature sonic boom
Lightning Crashes • Lightning heats the air and causes shock waves • This is what you hear as thunder • You see the lightning, then hear the thunder, but they both happen at the same time • It takes the sound about 5 seconds to travel 1 mile