* Mach number, in fluid mechanics, ratio of the velocity of a fluid to the velocity of sound in that fluid, named after Ernst Mach (1838-1916), an Austrian physicist and philosopher*. In the case of an object moving through a fluid, such as an aircraft in flight, the Mach number is equal to the velocity of the object relative to the fluid divided by the velocity of sound in that fluid The Mach number is termed as a dimensionless number because it is a ratio of two speeds. An Austrian philosopher and physicist Ernst Mach is after whom the Mach number is named. Due to it being a dimensionless quantity and not a measurable unit, the number is put after the term Mach for instance, Mach 4 and not 4 Mach. Mach Number Classificatio The Mach Number is a dimensionless value useful for analyzing fluid flow dynamics problems where compressibility is a significant factor.. The Mach Number can be expressed as. M = v / c (1) where . M = Mach number. v = fluid flow speed (m/s, ft/s Mach number can also determine if the flow is incompressible. The medium can either be gar or liquid. There are many scenarios where the medium can be flowing, but the boundary is stable, or the medium and boundary are both traveling, meaning that medium is at rest The peak Mach number on the surface of a conventional compressor blade is significantly higher than the inlet Mach number. Once the inlet Mach number exceeds about 0.7, the flow on the blade will become transonic, leading to performance deterioration. Figure 3.18 shows the surface Mach number distribution around a compressor aerofoil at low incidence for different levels of inlet Mach number

- The Mach number M is defined as the ratio of the true airspeed V to the speed of sound a in air at the flight altitude: (15) M = V / a For the calibration of Machmeters, the Mach number can be related to the ratio of the impact pressure to the static pressure q c / P by the following expressions
- The Mach number appears as a similarity parameter in many of the equations for compressible flows, shock waves, and expansions. When wind tunnel testing, you must closely match the Mach number between the experiment and flight conditions
- Mach Number. Mach, sometimes also referred to as a Mach number, is the ratio of the speed of an object to the speed of sound. Mach can be abbreviated as M, and is also sometimes abbreviated as Ma. For example, Mach 1 can be written as 1 M or 1 Ma
- The Mach angle and Prandtl-Meyer angle are also functions of the Mach number. These additional variables are used in the design of high speed inlets, nozzles and ducts. If you are an experienced user of this calculator, you can use a sleek version of the program which loads faster on your computer and does not include these instructions
- Mach number definition is - a number representing the ratio of the speed of a body (such as an aircraft) to the speed of sound in a surrounding medium (such as air). How to use Mach number in a sentence

Mach. Mach is a speed measurement based on the speed of sound. Since sound travels at different speeds in different conditions, the calculations here are given for 20°C in dry air at sea level. Mach is typically used in aviation and space exploration. Mach to Kilometers per hour formula Kilometers per hou NOTE: Mach speeds change with altitude, sea level is 762 mph, at altitude is 660 mph. 40,000 feet is the usual altitude. Please enter numbers only. Choose an altitude

Mach Number. The Mach number is used in fluid mechanics and is especially useful in studies involving supersonic aerodynamics. It is named after Ernst Mach (1838 - 1916), the Austrian physicist and philosopher who pioneered the study of supersonic projectiles. The Mach number is the ratio of the velocity of a fluid to the velocity of sound in that same fluid Mach number. In the flow of a fluid, the ratio of the flow velocity, V, at a given point in the flow to the local speed of sound, a, at that same point.That is, the Mach number, M, is defined as V/a.In a flowfield where the properties vary in time and/or space, the local value of M will also vary in time and/or space. In aeronautics, Mach number is frequently used to denote the ratio of the. Mach number. Wikipedia . Etymology . After the physicist Ernst Mach. Noun . Mach number (uncountable) The ratio of the velocity of a body to that of sound in the surrounding medium. Translations . ratio — See also translations at Mach

Mach number synonyms, Mach number pronunciation, Mach number translation, English dictionary definition of Mach number. also mach number n. Abbr. M The ratio of the speed of an object to the speed of sound in the surrounding medium. For example, an aircraft moving twice as.

This video lecture is for Exams Like GATE/ ESE(IES) /IAS and For any University course on Gas Dynamics or Compressible flow 1 Miles Per Hour to Mach Number = 0.0013: 70 Miles Per Hour to Mach Number = 0.092: 2 Miles Per Hour to Mach Number = 0.0026: 80 Miles Per Hour to Mach Number = 0.1051: 3 Miles Per Hour to Mach Number = 0.0039: 90 Miles Per Hour to Mach Number = 0.1182: 4 Miles Per Hour to Mach Number = 0.0053: 100 Miles Per Hour to Mach Number = 0.131 Mach number definition: the ratio of the speed of a body in a particular medium to the speed of sound in that... | Meaning, pronunciation, translations and example

Mach number is a measure of speed. When we say an aircraft is flying at Mach 1, it means that the speed of the vehicle is 343 m/s. Mach number is the ratio between the true airspeed of the aircraft and the local speed of sound. Since it is a ratio.. this video is all about the topic of Mach Number under mechanical engineering. And this Ernst Mach. And this is who the Mach number is named after. Ernst Mach, and he was this Austrian physicist and philosopher. He did a ton of research on shockwaves and soundwaves, and whatnot. So the Mach number is named after him. Relative speed of sound in solids, liquids, and gases * Kilometers per hour to Mach formula Mach*. Mach is a speed measurement based on the speed of sound. Since sound travels at different speeds in different conditions, the calculations here are given for 20°C in dry air at sea level. Mach is typically used in aviation and space exploration Mach Number is defined as the ratio of speed to the speed of sound in the medium in study. Since the speed of sound increases with the increase of temperature, the actual speed of an object travelling on Mach 1 will depend primarily on the fluid temperature around it. The other values upon which..

**Mach** **number** refers to a dimensionless value that is widely used in investigating dynamics of a compressible flow. It is mathematically arrived by the ratio of velocity of the body/fluid to the velocity of sound in air or any fluidic medium through which the body travels Examples of how to use mach number in a sentence from the Cambridge Dictionary Lab Mach numbers greater than unity famously create a 'sonic boom', where energy accumulates into a high intensity pressure wave caused by an aircraft or projectile moving through air. The Mach number can be used to analyse individual components of aircraft, rotating machinery, or more generally any fast moving object and correlated the component to a noise generation profile Mach number must be less than 1 to secure the subsonic flow in order to avoid the losses in the static pressure of the centrifugal compressor. A centrifugal compressor designer will determine the Mach number for each and every section of the compressor

If Mach number < 1 it implies the body travels with speed less than sound. For example, Mach 0.40 implies the body is traveling at 40% of the speed of sound and Mach 2 would mean the object travels with a speed twice that of the speed of sound. With the help of Mach number, various regimes are classified Mach number and Lockheed F-104 Starfighter · See more » Lockheed SR-71 Blackbird. The Lockheed SR-71 Blackbird is a long-range, Mach 3+ strategic reconnaissance aircraft that was operated by the United States Air Force. New!!: Mach number and Lockheed SR-71 Blackbird · See more » Low Earth orbi

- The isentropic Mach number is the Mach number you would have without any losses in the flow. This property is often used to investigate the ideal surface Mach number you would have without losses and walls without any friction (slip conditions)
- - Mach Number (V86-2) gick bra i årsdebuten då han var tvåa och jag tror att han kommer att få ett ganska bra år. Det är en rätt så fin häst som säkert kommer att gå framåt med loppet i kroppen. Men han är ingen startraket och blir över från innerspåret
- Mach 0.5 corresponds to a flow speed that's half the speed of sound, Mach 2 to a flow speed that's twice the speed of sound, and so on. Fluid flow can be broken up into two general regimes by Mach number: those less than Mach 1 are said to be subsonic, while those greater than Mach 1 are said to be supersonic.. A body moving through a fluid at speeds less than the speed of sound in the fluid.
- För andra betydelser, se Mach (olika betydelser).. Mach, även Machs tal eller machtal, förkortas M eller Ma, och är kvoten mellan hastigheten hos ett föremål och ljudhastigheten i dess omgivande medium.Machtalet bär sitt namn efter Ernst Mach, [1] österrikisk fysiker och filosof.Talet används ofta för att ange flygplans hastighet i luft, men kan användas för att ange.
- ated by la
- e the Mach number for velocity and speed of sound in feet per second: mach = machnumber([84.3905 33.7562 10.1269], 1116.4505) mach = 0.0819. Deter

80 Kilometres Per Hour to Mach Number = 0.0653: 3 Kilometres Per Hour to Mach Number = 0.0024: 90 Kilometres Per Hour to Mach Number = 0.0735: 4 Kilometres Per Hour to Mach Number = 0.0033: 100 Kilometres Per Hour to Mach Number = 0.0816: 5 Kilometres Per Hour to Mach Number = 0.0041: 200 Kilometres Per Hour to Mach Number = 0.163 * The Mach number is used in fluid mechanics and is especially useful in studies involving supersonic aerodynamics*.It is named after Ernst Mach (1838-1916), the Austrian physicist and philosopher who pioneered the study of supersonic projectiles A mach number is a number that describes speed.It is a measure of the speed of an object compared to the speed of sound.Mach number is given as a percentage compared to the local speed of sound. For example, half the speed of sound = Mach 0.5. = / Where v is the speed of the object, and a is the speed of sound.. It is named after the Austrian physicist Ernst Mach A mach meter produces an indication of mach number based on the ratio of dynamic pressure to static pressure. It does this by taking in pitot pressure and static pressure. An ASI differential capsule is then used to subtract static pressure from pitot pressure to leave dynamic pressure The dimensionless **Mach** **number** is a means to represent the speed of an object through a fluid (or the speed of a fluid over an object) relative to the speed of sound in the fluid.. More formally, the **Mach** **number** is defined as: M = V / a. where: M is the dimensionless **Mach** **number** V is the fluid or object speed a is the speed of sound in the fluid. For an ideal gas (such as air, when not under.

Mach number is the speed of an object moving through air, or any fluid substance, divided by the speed of sound as it is in that substance. Here we can calculate for Mach Number, Object Speed, Speed of Sound Use this page to learn how to convert between mach and meters/second. Type in your own numbers in the form to convert the units! ›› Quick conversion chart of mach to m/s. 1 mach to m/s = 340.29 m/s. 2 mach to m/s = 680.58 m/s. 3 mach to m/s = 1020.87 m/s. 4 mach to m/s = 1361.16 m/s. 5 mach to m/s = 1701.45 m/s. 6 mach to m/s = 2041.74 m/

Define relative Mach number. relative Mach number synonyms, relative Mach number pronunciation, relative Mach number translation, English dictionary definition of relative Mach number. also mach number n. Abbr. M The ratio of the speed of an object to the speed of sound in the surrounding medium MACH's operation will increase your venue's engagement from local people, produce leads in your direct message inbox, and automate response with custom replies. Phone number for pick up orders. 2.) Contest or Offer Ad. Targeting people who engaged your first ad In order to cover the desired Mach number range from subsonic to supersonic flow several axisymmetric nozzles with a mean exit diameter of 50 mm are easily exchangeable. dlr.de Durch leicht auswechselbare achsensymmetrische Düsen mit einem mittleren Durchmesser von 50 mm kann ein weiter Machzahlbereich von sub- bis zu supersonischer Strömung abgedeckt werden Torsdag 1 oktober. SPORT; SPEL; Logga in Premiu Mach definition, mach number. See more. The use and name of Mach numbers was proposed by Swiss engineer Jakob Ackeret in a 1929 lecture in Zurich. Ackeret named the number after the physicist Ernst Mach, who conducted an experiment photographing an object moving faster than the speed of sound in 1887.The name was quickly adopted by the broader scientific community

A dimensionless number named after Ernst Mach, used in momentum transfer in general and near/ultra sonic flow and throttling calculations in particular. Mach numbers < 1 are called subsonic, Mach numbers > 1 are called supersonic. Ma = V / V sound. V: velocity, V sound: velocity of sound in flui Mach number is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound.[1][2] For faster navigation, this Iframe is preloading the Wikiwand page for Mach number The ratio of the velocity of a body to that of sound in a surrounding medium. A Mach number of 0.8 or 1.2 means that the aircraft is flying at 0.8 or 1.2 times, respectively, the local speed of sound at that ambient temperature

- e if a flow can be treated as an incompressible flow. If M.
- ų žodynas . Mach number — The ratio of the velocity of a body to that of sound in a surrounding medium. A Mach number of 0.8 or 1.2 means that the aircraft is flying at 0.8 or 1.2 times, respectively, the local speed of.
- Mach Number Examples: A final question that comes up frequently is how fast is Mach 2, 3, 5, 10, or any other value besides Mach 1 at a given altitude. We first addressed this topic in a question regarding how fast is Mach 2 in miles per hour . Here, we pointed out that the Mach number is a multiple of the speed of sound
- Today, we call this ratio the Mach number (M): However, Mach himself did not coin the phrase. The term was first publicized in 1929 when Swiss engineer Jakob Ackeret (1898-1981) named the variable in honor of Mach during a lecture at the Eidgenossiche Technishe Hochschule in Zurich
- Mach Number and Temperature Contours for Dragonfly's entry to Titan.jpg 1,059 × 916; 511 KB Mach Number Flow Regimes.png 1,167 × 500; 24 KB Pitot cev.svg 1,590 × 1,140; 16 K
- Mach Number is defined as speed of object to speed of sound. It is an dimensionless number and it has no units

Mach number 'mäk-n a number representing the ratio of the speed of a body to the speed of sound in a surrounding medium (as air) <a Mach number of 2 indicates a speed that is twice that of sound> Medical dictionary Mach number - the ratio between the speed of an object moving through a fluid medium and the speed of sound in the same medium

- Air at a Mach number 3.0, a pressure 50 kPa, and a temperature 200K undergoes compression shock at a corner of {eq}\theta {/eq}=20 degrees , as shown in the figure below
- Mach Number Mach number is the speed of an object moving through the air divided by the speed of sound in those current conditions. The speed of sound is directly related to temperature and density so it is constantly varying. The accepted speed of sound at sea level and standard atmospheric conditions is 661.The Mach number appears as a similarity parameter in many of the equations for.
- Hur ska jag säga Mach number i Engelska? Uttal av Mach number med 2 ljud uttal, 1 synonym, 1 innebörd, 12 översättningar, 8 meningar och mer för Mach number
- Mach (mahk), Ernst, scientist in Hapsburg Empire, 1838-1916. See: Mach band, Mach number. CASP8 A gene on chromosome 2q33-q34 that encodes a protein belonging to the cysteine-aspartic acid protease (caspase) family which, once activated by proteolytic processing, plays a central role in the execution phase of cell apoptosis, as well as various stages of.
- Mach number definition: [alsom- n-] a number representing the ratio of the speed of an object to the speed of sound in the surrounding medium, as air, through which the object is movingOrigin of Mach numberafter E. Mach (1838-1916), Austrian physicist..
- Introduction. The area-Mach number relation (AMR from now on), is important when analyzing nozzle flows. In this post, I'm not going to go through the derivation of the equation because I derive it in this video.. I will be taking the final equation and showing you a few different methods of solution, along with some MATLAB code that you can use in your own programs

The Mach number is named after Austrian physicist and philosopher Ernst Mach, a designation proposed by aeronautical engineer Jakob Ackeret. As the Mach number is a dimensionless quantity rather than a unit of measure, with Mach, the number comes after the unit; the second Mach number is Mach 2 instead of 2 Mach (or Machs) Compute Mach number using velocity and speed of sound. expand all in page. Library: Aerospace Blockset / Flight Parameters Description. The Mach Number block computes the Mach number. The Mach number is defined as Mach Number Technique Defined [NAT Doc 007, ¶7.1.1.]The term 'Mach Number Technique' is used to describe a technique whereby subsonic turbojet aircraft operating successively along suitable routes are cleared by ATC to maintain appropriate Mach Numbers for a relevant portion of the en route phase of their flight

mach. Also, Mach number. [1935 40] * * * physics in fluid mechanics, ratio of the velocity of a fluid to the velocity of sound in that fluid, named after Ernst Mach (Mach, Ernst) (1838-1916), an Austrian physicist and philosopher. In th mach number becomes available as a system field function when you go to compressible flow with idea gas so not sure why you cant use this so try doing a user guide tutorial like the subsonic slow naca-type intake on

The Mach number is measured with the use of a flight instrument known as a machmeter. Found in the cockpit of most high-speed aircraft, including private jets, a machmeter can be combined with an air speed indicator (ASI) as part of the jet's air data computer. Speed ratios are normally separated into the categories of subsonic, transonic, supersonic, and hypersonic, which classify air and. 1000万語収録!Weblio辞書 - Mach number とは【意味】マッハ数... 【例文】Austrian physicist and philosopher who introduced the Mach number and who founded logical positivism (1838-1916)... 「Mach number」の意味・例文・用例ならWeblio英和・和英辞 The Mach number is named after Austrian physicist and philosopher Ernst Mach, a designation proposed by aeronautical engineer Jakob Ackeret. Because the Mach number is often viewed as a dimensionless quantity rather than a unit of measure, with Mach, the number comes after the unit; the second Mach number is Mach 2 instead of 2 Mach (or Machs) Mach Speed is when an object moves faster than the speed of sound. For normal and dry conditions and temperature of 68 degrees F, this is 768 mph, 343 m/s, 1,125 ft/s, 667 knots, or 1,235 km/h. If you've ever watched a movie with fighter jets in it, chances are you've heard them talk about Mach numbers MACH NUMBER ' Velocity of Interest Velocity of Sound (at the given atmospheric conditions ) Speed of Sound (KTAS )' 29 .06 518 .7 &3.57 A Where A 'altitude (K ft) 8-2.1 [1] [2] MACH NUMBER and AIRSPEED vs ALTITUDE MACH NUMBER is defined as a speed ratio, referenced to the speed of sound, i.e

Mach number (Ma or M) is the speed of an object moving in air, divided by the speed of sound at that particular conditions, including temperature and pressure.At Standard Sea Level and temperature 15 degrees Celsius, the speed of sound is 761.2 miles per hour (mph) = 340.3 meters per second (m/s) = 1225 kph = 1116 foot per second (ft/s) = 661.5 knots (kn, kt or kts) Title: Microsoft PowerPoint - Topic 5 - Area-Mach Number Relation - Students.pptx Author: devenpor Created Date: 2/2/2010 4:59:57 P $\begingroup$ @mins There are two limits: IAS (Vne) and critical Mach number (Mcr). Too much IAS can exceed structural limits. Over critical mach you get undesirable compressability effects (more drag, mach tuck) etc. In warm dense air the critical mach num is higher than the Vne, so you don't need to worry about exceeding it Mach number is useful because the fluid behaves in a similar way at the same Mach number. So, an aircraft travelling at Mach 1 at sea level (340.3 m/s, 1,225.08 km/h) will experience shock waves in much the same manner as when it is travelling at Mach 1 at 11,000 m (36,000 ft), even though it is travelling at 295 m/s (654.632 mph, 1,062 km/h, 86% of its speed at sea level) All information you need for mach number. Sixty-four years ago today, the No. 1 USAF/Bell X-2 rocket-powered flight research aircraft reached a record speed of 2,094 mph with USAF Captain Milburn G. Mel Apt at the controls

Mach number is the speed of an object moving through the air divided by the speed of sound in those current conditions. The speed of sound is directly related to temperature and density so it is constantly varying. The accepted speed of sound at sea level and standard atmospheric conditions. We can also calculate the Mach number at each port using this equation, where gamma is the specific heat. Here, we've plotted the variation in pressure ratio and Mach number versus the normalized nozzle distance for each flow rate in our converging nozzle. At the throat, the Mach number does not exceed 1, meaning that the flow is choked mach numbers mach 1, et cetera— ratio of velocity of an object to the velocity of sound (named after Ernst Mach, Austrian physicist) Eponyms, nicknames, and geographical games **Mach** **number** - WordReference English dictionary, questions, discussion and forums. All Free

* число Маха относительная скорость тела или точки (участка) на нем по отношению к окружающему воздуху или другой среде или отношение скорости одной среды к скорости другой, ее окружающей*. Символы М или NMa. см. number Mach number: translation. Macho skaičius statusas T sritis Gynyba apibrėžtisskaičius statusas T sritis Gynyba apibrėžti Synonyms for Mach numbers in Free Thesaurus. Antonyms for Mach numbers. 1 synonym for Mach: Ernst Mach. What are synonyms for Mach numbers

- Acronym Definition MN Minnesota (US postal abbreviation) MN Main MN Mobile Node MN Minute MN Model Number (manufacturer code) MN Monaco MN Minor (AT&T) MN Mongolia (ISO country code, top level domain) MN Midnight MN Music News MN Montenegro (Yugoslavia) MN Manganese MN Master of Nursing MN Multinational MN Mach Number (aviation) MN Mobile Network MN.
- The pressure Mach number relationship Before going further in the mathematical derivation it is worth looking at the physical meaning of equation . The term is always positive (because all the three terms can be only positive). Now, it can be observed that can be positive or negative depending on the and Mach number
- Mach number is a measure of the compressibility characteristics of fluid flow: the fluid (air) behaves under the influence of compressibility in a similar manner at a given Mach number, regardless of other variables.As modeled in the International Standard Atmosphere, dry air at mean sea level, standard temperature of 15 °C (59 °F), the speed of sound is 340.3 meters per second (1,116.5 ft/s)
- Therefore, the only factor that affects relationship between the cross area and the Mach number is \(M^2 -1\). For \(M <1\) the Mach number is varied opposite to the cross section area. In the case of \(M > 1\) the Mach number increases with the cross section area and vice versa. The special case is when \(M=1\) which requires that \(dA=0\)

Actually, Mach number is the speed of the plane or air vehicles, or speed of the air, measured in units of the speed of the sound. It represents the speed of an object when it is traveling at the speed of sound. A plane traveling at a speed of Mach 2 is going twice th The Mach number varies from essentially zero in the reservoir to Mach 2.0 at the exit. Plot on graph paper the variation of the ratio of dynamic pressure to total pressure as a function of Mach number; that is, plot q/ p o versus M from M = 0 to M = 2.0. Solution 4.33 ( ). A dimensionless number giving the ratio of the speed of an object to the ambient speed of sound in the surrounding medium, {\rm Ma}\equiv {u\over u_{\rm sound}}. It is named in honor of physicist Ernst Mach. See also: Speed of Soun The Mach family name was found in the USA, the UK, Canada, and Scotland between 1840 and 1920. The most Mach families were found in the USA in 1920. In 1840 there were 2 Mach families living in Pennsylvania. This was about 33% of all the recorded Mach's in the USA. Pennsylvania had the highest population of Mach families in 1840 The Mach number is different at different altitudes for the same velocity of the airplane or flying vehicle. An alternative formula for the Mach Number is then, Mach Number, M = Velocity of Flying Vehicle divided by squareroot (gamma*specific-gas-constant*temperature)

** Mach Support Help Desk**. Self-directed. Users access the FAQ's, videos, and manuals to learn more about the software and find solutions to common problems and questions. Help & Learning. Learning the basics through these means will be of great benefit to your quality of cutting and the projects you can create Mach number: Mach: $100 note, being 100 in number, county subdivision, group of 100, large number, number 100, number third from decimal point, numbers 100 to 999, position third from decimal point, years of a century: hundred: $20 bill, amounting to 20 in number, group of 20, number 20, numbers 20 to 29, period from age 20 to 29, years 1920 to. In this paper, we perform direct numerical simulations (DNS) of turbulent boundary layers with nominal free-stream Mach number ranging from 0.3 to 12. The main objective is to assess the scalings with respect to the mean and turbulence behaviours as well as the possible breakdown of the weak compressibility hypothesis for turbulent boundary layers at high Mach numbers ( M > 5)

- Mach Number: Mach Number: Object Speed: Speed of Sound: where, M = Mach Number, v = Object Speed, a = Speed of Sound. Related Calculator
- Mach number n often not cap 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, (Often shortened to) Mach (C19: named after Ernst Mach
- Swedish Translation for inflow Mach number - dict.cc English-Swedish Dictionar
- What is Mach Number and importance of Mach Number? The ratio of velocity of fluid, in an undisturbed stream, to the velocity of sound wave, is known as Mach number. It gives us an important information about the type of flow. In general, the flow of a fluid is divided into the following four types depending upon the Mach number

- Mach number Macho skaičius statusas T sritis Standartizacija ir metrologija apibrėžtisskaičius statusas T sritis Standartizacija ir metrologija apibrėžti
- The MACH project was established to achieve CE certification and market entry of EXCOR®. The project was a success as both of these goals have been achieved as of 2020. EIT Health is eager to support a project of such importance to the growing number of children in end-stage heart failure
- (Cap. M.) The ratio of the speed of an object to the speed of sound in the medium (usually air) through which the object is traveling: e.g., an aircraft traveling at twice the speed of sound is said to be going at Mach 2. Named after Ernst Mach