mach-number

mach number

noun
Also, Mach number.


Origin:
1935–40

Dictionary.com Unabridged

mach

[mahk]
noun
a number indicating the ratio of the speed of an object to the speed of sound in the medium through which the object is moving. Abbreviation: M
Also, Mach.
Also called mach number, Mach number.


Origin:
after E. Mach

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
Mach1 (mæk)
 
n
short for Mach number

Mach2 (German max)
 
n
Ernst (ɛrnst). 1838--1916, Austrian physicist and philosopher. He devised the system of speed measurement using the Mach number. He also founded logical positivism, asserting that the validity of a scientific law is proved only after empirical testing

Mach number
 
n
(often not capital) Often shortened to: Mach the ratio of the speed of a body in a particular medium to the speed of sound in that medium. Mach number 1 corresponds to the speed of sound
 
[C19: named after Ernst Mach]

Collins English Dictionary - Complete & Unabridged 10th Edition
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Etymonline
Word Origin & History

Mach
measure of speed relative to the speed of sound (technically Mach number), 1937, named in honor of Austrian physicist Ernst Mach (1838-1916).
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
Mach   (mäk, mäKH)  Pronunciation Key 
Austrian physicist and philosopher who experimented with supersonic projectiles and the flow of gases, obtaining early photographs of shock waves and gas jets. His work laid an important foundation for later developments in the science of projectiles and aeronautical design, and the Mach number and Mach bands were named for him.
Mach number  
The ratio of the speed of a body to the speed of sound in a particular medium, usually the Earth's atmosphere. For example, an aircraft flying through air at twice the speed of sound has a Mach number of 2. The Mach number of an aircraft travelling at a given velocity depends on the altitude of the aircraft and other atmospheric conditions that affect the speed of sound near the aircraft. See also subsonic, supersonic, transonic.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary
Mach number [(mahk)]

The speed of an object, measured in multiples of the speed of sound. Thus, an airplane traveling at the speed of sound is said to be at Mach 1; at twice the speed of sound, it is said to be at Mach 2.

Note: The unit is named after Ernst Mach, an Austrian physicist of the nineteenth century.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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