1. The speed of sound varies with temperature, elevation, and other atmospheric conditions but is approximately 1130 ft/s or 758 mph at 20°C. 2. Sound travels fastest in solids, slower in liquids, and slowest in gases, with speed determined by the density and proximity of particles. 3. The fastest planes can travel at over 7000 mph, achieving Mach 9.6, while the fastest car achieved 760 mph, breaking the sound barrier.

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COMPUTER/LAB PROJECTCOMPUTER/LAB PROJECT
One two three fourOne two three four

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3. 3
WHAT IS THE SPEED OF
SOUND
• The speed of sound is 1130 ft/second at 20
degrees C.
• The speed of sound is 758 m/hr at 20
degrees C.
• It varies with elevation due to air pressure,
air density, and temperature.

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How does speed travel in
different states of matter?
• Sound travels fastest in a solid.
• Sound travels slower in a liquid.
• Sound travels the slowest in air.
• The closer the particles in a substance the
faster sound travels.
• Think of a clank underwater in a swimming
pool.

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Formulas
• Speed = distance/time
• Mach speed = Speed miles per hour/758
miles per hour.
• Conversion = ft/sec x 60sec/1min x
60min/1hour x 1mile/5280ft
• Convert the fastest Equla 22 at around 1700
ft/sec to mph – does it make a sonic boom?

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Fastest Human
• His name is Usain Bolt
• He is one of the fastest.
• He can run 100 meters in
9.6 seconds.
• Mr. Albrandt would be a
close second.
• Tyson Gay can jet also.
U
sain
Bolt

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Fastest Car
• The fastest car was the
British made Thrust
SSC.
• It could travel 760.1
miles per hour.
• And yes it did break
the speed of sound!

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MORE ON FAST CAR
• They had to run in the
desert salt flats to have
enough room.
• It took 250000 gallons of
fuel to complete project –
much of it was raised
with internet donations.
• The cockpit was like a jet
plane with many
computers.

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SPEED FACTS
• SPEED NEVER HAD A BAD DAY
• SPEED KILLS
• YA GOT SPEED – EVERYTHING ELSE
WILL FOLLOW
• YA CAN’T TEACH SPEED
• HAVE SPEED – WILL TRAVEL WITH
EXTREME QUICKNESS

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Fastest Plane
• The fastest plane is the X-
43.
• It can move at 7000 miles
per hour.
• Converting that to Mach
speed you are traveling at
Mach 9.6.
• Now that is what I call
speed.
• It is rumored that Skunk
Works may have a plane
that can do Mach 10

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FASTEST PLANE VIDEO LINK
• http://www-pao.ksc.nasa.gov/kscpao/videos/meta

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Why is xr-71 so hot in a high
cold place?
• As you go up in elevation temperature
drops because of sparse particle placement.
• The temperature gets to be –70 degrees C at
80000 feet elevation.
• Even though it is so cold the friction caused
by the planes excessive speed makes the
plane hot.

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My reaction time to hit a 95 mph
fastball.
• Web site for activity
http://www.exploratorium.edu/baseball/reactionti
• My reaction time was .25 seconds.
• How fast are you?

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What is a shock wave?
• As a plane travels faster
than the speed of sound it
pushes the air in front of
it.
• The waves cannot travel
faster than the speed of
sound so they pile up.
• These piled up waves are
called shock waves.

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Factors that affect the speed of
sound in air.
• Temperature of the air.
• Density of the air.
• Altitude that you are at.

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Some key term definitions.
• Speed is distance traveled per time.
• Mach is the speed of sound which is 758
miles per hour at 20 degrees C.
• Kinetic is a term related to motion.
• Sonic boom is created by shock waves
moving out from plane towards ground and
going through a sudden pressure change
that hits your eardrum.

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Websites to consider.
• http://www.pbs.org/wgbh/nova/barrier/men.html
• http://www.exploratorium.edu/baseball/reactionti
• http://www.grc.nasa.gov/WWW/K-12/a

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Lab procedure
• Measure baseball pitching distance of 60.5 feet
from pitching mark to wall.
• Have someone time the ball from release to when
it hits the wall.
• Record the total distance and total time in feet and
seconds.
• To get speed divide distance by time.
• To get speed in miles per hour use dimensional
analysis formula above.
• To get Mach number divide this value by 758
miles per hour.

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Extra Credit
• Randy Johnson threw
a baseball that killed a
bird in a professional
baseball game.
• He can throw a
baseball just over 100
mph.
• http://www.youtube.co
m/watch?
v=viI2YQoucBE&wat
ch_response