Machn.

Brit.

/mak/,

/mɑːk/,

/mɑːx/, U.S.

/mɑk/,

/mɑx/

Origin: From a proper name. Etymon: proper name Mach.

Etymology: < the name of Ernst Mach (1838–1916), Moravian-born Austrian physicist and philosopher. See also Machian adj., Machism n.

attributive and in the genitive. Designating certain concepts associated with Mach's work on aerodynamics.

a. Mach's principle n. [after German Machsches Prinzip (A. Einstein 1918, in Ann. d. Physik 55 241)] Physics the proposition that the inertia of a body depends on the distribution of matter in the universe.

ΘΚΠ

the world > matter > physics > mechanics > dynamics > [noun] > inertia > specific principle

Mach's principle1918

1918 Sci. Abstr. A. 21 352 Mach's Principle by which the G-field is determined without residue by the masses of the bodies.

1930 L. Silberstein Size of Universe ii. 73 Einstein in his ‘cosmological contemplations’ of 1916 set out with the resolute plan of satisfying what he called ‘Mach's principle’ (relativity of inertia).

1951 Ann. Math. 53 472 In general relativity Mach's principle is interpreted as stating that the nature of space-time is determined by the matter present.

1965 J. D. North Measure of Universe xiv. 306 Did Bondi think that ‘Mach's Principle’ was essential to any satisfactory physical theory?

1977 J. Narlikar Struct. Universe v. 169 Mach's principle, and its implication that inertia is not an intrinsic property of matter but is due to the background of distant stars, have received a mixed reception in the world of theoretical physics.

1987 Nature 6 Aug. 501/2 Ernst Mach advocated that..the vanishing cosmic rotation is part of the empirical basis of what is known as Mach's principle.

b. Mach angle n. (also Mach's angle) the angle between a generator of a Mach cone and its axis, the cosecant of which equals the Mach number of the body generating the cone.

ΘΚΠ

society > travel > air or space travel > specific movements or positions of aircraft > aerodynamic forces and concepts > [noun] > Mach cone or angle

Mach angle1930

Mach cone1933

1930 J. Dougall & W. M. Deans tr. P. P. Ewald Physics Solids & Fluids v. 262 During a small interval of time τ, a point source of disturbance expands to a sphere of radius cτ, the centre of which has moved through a distance qτ. The cone touches this sphere, so that sin a = cτ/qτ = c/q... a is called Mach's angle.

1938 Jrnl. Royal Aeronaut. Soc. 42 194 The part of the wave at a distance from the shell moves normal to itself with the speed of sound and this fact determines the angle it makes with the direction of motion of the shell (the ‘Mach angle’).

1990 IMA Jrnl. Appl. Math. 44 104 This plane wave therefore propagates into the fluid at the Mach angle.

c. Mach cone n. a conical wavefront extending backwards from a body moving at supersonic speed, with a vertex at the body's nose.

ΘΚΠ

society > travel > air or space travel > specific movements or positions of aircraft > aerodynamic forces and concepts > [noun] > Mach cone or angle

Mach angle1930

Mach cone1933

1933 Proc. Royal Soc. A. 139 307 The Mach cone x = y and z = 1 would satisfy the required conditions.

d. Mach number n. (also †Mach's number) [after German Mach'sche Zahl (J. Ackeret 1929, in Schweizerische Bauzeitung 12 Oct. 179)] a dimensionless number representing the ratio of the relative speed of a body and a fluid (esp. the air) to the local speed of sound in the fluid. Mach one (or two, etc.) n. (also Mach 1, 2, etc.) a supersonic speed corresponding to a Mach number of one (or two, etc.). Mach air-speed n. a speed expressed as a Mach number.

ΘΚΠ

society > travel > air or space travel > specific movements or positions of aircraft > aerodynamic forces and concepts > [noun] > Mach number

Mach number1937

1937 R. A. Dodge & M. J. Thompson Fluid Mech. xiii. 370 The ratio V/c will be found to appear in all flow problems where compressibility is an important factor. It is known as Mach's number..in honor of the Austrian scientist.

1947 Time 8 Sept. 76/2 During both flights it reached ‘mach ·828’.

1948 ‘N. Shute’ No Highway 34 It was diving at round about Mach unity, and the wings came off.

1953 Sci. News 29 93 The non-dimensional quantity M = V/a is defined as the ‘Mach Number’ of the flow.

1957 Spaceflight 1 51/1 In a rocket exhaust where the gases are moving at 6,000 ft./sec.,..the velocity of sound is 2,000 ft./sec., so the Mach No. is 3.

1967 Technol. Wk. 23 Jan. 29/2 (advt.) McDonnell testing and development facilities range from man-rated space chambers to Mach 28 wind tunnels.

1969 Jrnl. Inst. Navigation 22 iii. p. v (advt.) Barometric airspeed indication and servoed digital mach read-out are happily united in this Combined Mach Airspeed Indicator.

1990 Q. Jrnl. Mech. & Appl. Math. 43 478 These modes will not be present in high-Mach-number-flows.

1991 Star-Ledger (Newark, New Jersey) 20 Jan. i. 29/1 The speed of conflict has changed... In this war, it's moving at something like Mach Two.

Compounds

attributive and in the genitive. Designating an optical illusion first investigated by Mach (in Sitzungsber. der Königl. Akad. der Wissensch.: Math.-Nat. Classe (1865)), in which a place where the spatial rate of variation of surface brightness abruptly increases or decreases (as at the inner and outer edges of an indistinct shadow) may appear unaccountably dark or bright; Mach bands n. illusory dark or bright bands perceived at such a place.

ΘΚΠ

the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > illusion of

Mach bands1932

1932 W. M. Deans tr. R. W. Pohl Physical Princ. Mech. & Acoustics i. 4 Mach's bands have led to much trouble in the carrying out of physical observations.

1936 Brit. Jrnl. Psychol. 27 103 The same generalizations can be made about the Mach effect on a rotating colour wheel.

1965 Graham & Brown in C. H. Graham et al. Vision xvi. 474/2 Mach rings with spatial variations in color.

1965 F. Ratliff Mach Bands ii. 43 The Mach bands appear at once in the shadow cast on a piece of white paper by the edge of a card held under a fluorescent desk lamp, which provides an extended source of light.

1971 Jrnl. Gen. Psychol. 84 118 Von Bekesy has demonstrated a cutaneous analogy to Mach's Rings.

1986 Amer. Artist May 36 Our visual system generates ‘Mach bands’, which increase or decrease the intensity of adjacent objects.

1991 Sci. Amer. May 44/1 Other illusions include the Mach bands (apparent bright and dark bands adjacent to transitions from dark to light).

This entry has been updated (OED Third Edition, March 2000; most recently modified version published online March 2022).

单词	mach
释义	Machn. Brit. /mak/, /mɑːk/, /mɑːx/, U.S. /mɑk/, /mɑx/ Origin: From a proper name. Etymon: proper name Mach. Etymology: < the name of Ernst Mach (1838–1916), Moravian-born Austrian physicist and philosopher. See also Machian adj., Machism n. attributive and in the genitive. Designating certain concepts associated with Mach's work on aerodynamics. a. Mach's principle n. [after German Machsches Prinzip (A. Einstein 1918, in Ann. d. Physik 55 241)] Physics the proposition that the inertia of a body depends on the distribution of matter in the universe. ΘΚΠ the world > matter > physics > mechanics > dynamics > [noun] > inertia > specific principle Mach's principle1918 1918 Sci. Abstr. A. 21 352 Mach's Principle by which the G-field is determined without residue by the masses of the bodies. 1930 L. Silberstein Size of Universe ii. 73 Einstein in his ‘cosmological contemplations’ of 1916 set out with the resolute plan of satisfying what he called ‘Mach's principle’ (relativity of inertia). 1951 Ann. Math. 53 472 In general relativity Mach's principle is interpreted as stating that the nature of space-time is determined by the matter present. 1965 J. D. North Measure of Universe xiv. 306 Did Bondi think that ‘Mach's Principle’ was essential to any satisfactory physical theory? 1977 J. Narlikar Struct. Universe v. 169 Mach's principle, and its implication that inertia is not an intrinsic property of matter but is due to the background of distant stars, have received a mixed reception in the world of theoretical physics. 1987 Nature 6 Aug. 501/2 Ernst Mach advocated that..the vanishing cosmic rotation is part of the empirical basis of what is known as Mach's principle. b. Mach angle n. (also Mach's angle) the angle between a generator of a Mach cone and its axis, the cosecant of which equals the Mach number of the body generating the cone. ΘΚΠ society > travel > air or space travel > specific movements or positions of aircraft > aerodynamic forces and concepts > [noun] > Mach cone or angle Mach angle1930 Mach cone1933 1930 J. Dougall & W. M. Deans tr. P. P. Ewald Physics Solids & Fluids v. 262 During a small interval of time τ, a point source of disturbance expands to a sphere of radius cτ, the centre of which has moved through a distance qτ. The cone touches this sphere, so that sin a = cτ/qτ = c/q... a is called Mach's angle. 1938 Jrnl. Royal Aeronaut. Soc. 42 194 The part of the wave at a distance from the shell moves normal to itself with the speed of sound and this fact determines the angle it makes with the direction of motion of the shell (the ‘Mach angle’). 1990 IMA Jrnl. Appl. Math. 44 104 This plane wave therefore propagates into the fluid at the Mach angle. c. Mach cone n. a conical wavefront extending backwards from a body moving at supersonic speed, with a vertex at the body's nose. ΘΚΠ society > travel > air or space travel > specific movements or positions of aircraft > aerodynamic forces and concepts > [noun] > Mach cone or angle Mach angle1930 Mach cone1933 1933 Proc. Royal Soc. A. 139 307 The Mach cone x = y and z = 1 would satisfy the required conditions. d. Mach number n. (also †Mach's number) [after German Mach'sche Zahl (J. Ackeret 1929, in Schweizerische Bauzeitung 12 Oct. 179)] a dimensionless number representing the ratio of the relative speed of a body and a fluid (esp. the air) to the local speed of sound in the fluid. Mach one (or two, etc.) n. (also Mach 1, 2, etc.) a supersonic speed corresponding to a Mach number of one (or two, etc.). Mach air-speed n. a speed expressed as a Mach number. ΘΚΠ society > travel > air or space travel > specific movements or positions of aircraft > aerodynamic forces and concepts > [noun] > Mach number Mach number1937 1937 R. A. Dodge & M. J. Thompson Fluid Mech. xiii. 370 The ratio V/c will be found to appear in all flow problems where compressibility is an important factor. It is known as Mach's number..in honor of the Austrian scientist. 1947 Time 8 Sept. 76/2 During both flights it reached ‘mach ·828’. 1948 ‘N. Shute’ No Highway 34 It was diving at round about Mach unity, and the wings came off. 1953 Sci. News 29 93 The non-dimensional quantity M = V/a is defined as the ‘Mach Number’ of the flow. 1957 Spaceflight 1 51/1 In a rocket exhaust where the gases are moving at 6,000 ft./sec.,..the velocity of sound is 2,000 ft./sec., so the Mach No. is 3. 1967 Technol. Wk. 23 Jan. 29/2 (advt.) McDonnell testing and development facilities range from man-rated space chambers to Mach 28 wind tunnels. 1969 Jrnl. Inst. Navigation 22 iii. p. v (advt.) Barometric airspeed indication and servoed digital mach read-out are happily united in this Combined Mach Airspeed Indicator. 1990 Q. Jrnl. Mech. & Appl. Math. 43 478 These modes will not be present in high-Mach-number-flows. 1991 Star-Ledger (Newark, New Jersey) 20 Jan. i. 29/1 The speed of conflict has changed... In this war, it's moving at something like Mach Two. Compounds attributive and in the genitive. Designating an optical illusion first investigated by Mach (in Sitzungsber. der Königl. Akad. der Wissensch.: Math.-Nat. Classe (1865)), in which a place where the spatial rate of variation of surface brightness abruptly increases or decreases (as at the inner and outer edges of an indistinct shadow) may appear unaccountably dark or bright; Mach bands n. illusory dark or bright bands perceived at such a place. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > illusion of Mach bands1932 1932 W. M. Deans tr. R. W. Pohl Physical Princ. Mech. & Acoustics i. 4 Mach's bands have led to much trouble in the carrying out of physical observations. 1936 Brit. Jrnl. Psychol. 27 103 The same generalizations can be made about the Mach effect on a rotating colour wheel. 1965 Graham & Brown in C. H. Graham et al. Vision xvi. 474/2 Mach rings with spatial variations in color. 1965 F. Ratliff Mach Bands ii. 43 The Mach bands appear at once in the shadow cast on a piece of white paper by the edge of a card held under a fluorescent desk lamp, which provides an extended source of light. 1971 Jrnl. Gen. Psychol. 84 118 Von Bekesy has demonstrated a cutaneous analogy to Mach's Rings. 1986 Amer. Artist May 36 Our visual system generates ‘Mach bands’, which increase or decrease the intensity of adjacent objects. 1991 Sci. Amer. May 44/1 Other illusions include the Mach bands (apparent bright and dark bands adjacent to transitions from dark to light). This entry has been updated (OED Third Edition, March 2000; most recently modified version published online March 2022). > see also also refers to : -machcomb. form < n.1918 see also
随便看	inequation inequations inequi inequi- inequiaxed inequiaxial inequicostate inequidistant inequilater inequilateral inequilateral shell inequilaterous inequilibrity inequilobate inequilobed inequipotential inequipotentiality inequitable inequitably inequitate inequities inequity inequivalence inequivalent inequivalve

Machn.

Compounds

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