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The Speed of Sound. How can you determine how far a thunder storm is away from you?. Speed of Sound. Much slower than the speed of light (values for air) Light – 300,000,000 m/s Sound – 332 m/s. Calculating Speed of Sound. Assuming no pressure change from atmospheric, V = 332 + 0.59T
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How can you determine how far a thunder storm is away from you?
Speed of Sound • Much slower than the speed of light (values for air) • Light – 300,000,000 m/s • Sound – 332 m/s
Calculating Speed of Sound • Assuming no pressure change from atmospheric, V = 332 + 0.59T • The speed of sound in air at 0C is 332m/s, the speed increases by 0.59m/s for every degree celsius raised
Practice Question • What is the speed of sound in this room?
Changing the Medium • Sound can travel through solid, liquid or gas • Speed of sound depends on three things: • Density of particles • Closer particles are together – faster vibration can travel • Gas – slow, solid – fast • Sound travels faster on a humid day
Temperature of Particles • Faster the particles move, the quicker the vibration can be transferred • Warm – Fast, Cold – slow • Mass of the Particles • Heavier the particles, the slower the vibration travels
Questions: • Calculate the speed of sound if the temperature is: a) 1C b) 30C c) -10 C • If the frequency of a radio wave is 102.1Mhz and the temperature of the air outside is 15C, what is the wavelength of the radio wave? • A student is located 100m away from the school’s bell. If the bell rings, how long will it take the sound to reach the student’s ear if the temperature outside is -15 C? • A swimmer is under the water while their friend is on the shore. If they are both the same distance away from a boat that is approaching, who will hear the boat first? • Will sound travel faster at sea level or at the top of a mountain? The equator or the north pole? Explain.
Reflection of Sound • Echoes – sound that reflects off a barrier and returns to the source • Only use the following formula for echoes: v = 2d/t V – speed of sound d – distance from source to reflective barrier t – time for sound to return
Sonar • Uses sound to detect things underwater • Process called echolocation – by analyzing echoes (reflected sound) we can detect objects
Echolocation • Bats and dolphins use echolocation to find prey and locate things around themselves • http://www.youtube.com/watch?v=gZxLUNHEmPw
Homework • How long would an echo take to return from the Titanic if it is 4.0km below the surface of the Atlantic? The speed of sound in sea water is 1531m/s. • A ship is sailing on a foggy night. The captain is worried about ice bergs but has no radar. The captain sounds the ships horm and hears the echo 2.4s later. If the air temperature is -10C, how far away is the ice berg. • Research and explain how bats use echolocation to determine the location of their prey.