
Mach Number Activity


Open the slide called Mach Number
and read the definition of Mach number.
Various military aircraft
have Mach numbers from 1.6 to over 3. Do you know what that means?
The unitless Mach
number was named after the Austrian physicist Ernst Mach.
The Mach number is ratio of the speed of the aircraft to the
speed of sound .
An airplane
flying at less than Mach 1 is traveling at
subsonic
speeds; at about Mach 1, or
transonic ,
it is at the speed of sound,
and greater than Mach 1 is
supersonic .
An aircraft traveling
at Mach 2 is traveling at twice the speed of sound.
The speed of sound on an average day at sea level is 761 mph. The
speed of sound depends on the composition and temperature of the air
and it decreases with altitude. For the following problems, assume
that the speed of sound is constant and equal to 740 mph.
 Use the definition
of Mach number obtained from the Mach Number slide
and the information above to determine the speed of a jet at Mach 3.
 Convert the speed
of sound units of mph to km/hr.
 Let's find the
top speed of some interesting jets. The maximum Mach number of the jets
listed can be found on the World Wide Web. Simply go to the link provided,
B747, F18, and SR71A. Use the data
to fill in the Mach number, then compute and fill in the speeds in
the table below.
 The
X15 was a research aircraft
designed and built for NASA. Using its maximum Mach number,
compute its maximum speed.
Max Mach Number,
= __________________
Max Speed , km/hr =
______________________