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Oceanic whitetip shark swimming near a diver. The oceanic whitetip shark is a large requiem shark inhabiting tropical and warm temperate seas. It has a stocky body with long, white-tipped, rounded fins. The species is typically solitary but can congregate around food concentrations. It is found worldwide between 45°N and 43°S latitudes in ...
Siddhartha Gautama, [e] most commonly referred to as the Buddha ('the awakened'), [f] [g] was a wandering ascetic and religious teacher who lived in South Asia during the 6th or 5th century BCE [4] [5] [6] [c] and founded Buddhism.
[o] The main island of Taiwan, also known as Formosa, lies between the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the northeast, and the Philippines to the south.
- Earth
- History
- Basic Concepts
- Equations
- Dependence on The Properties of The Medium
- Altitude Variation and Implications For Atmospheric Acoustics
- Details
- Effect of Frequency and Gas Composition
- Mach Number
- Experimental Methods
In Earth's atmosphere, the speed of sound varies greatly from about 295 m/s (1,060 km/h; 660 mph) at high altitudes to about 355 m/s (1,280 km/h; 790 mph) at high temperatures.
Sir Isaac Newton's 1687 Principia includes a computation of the speed of sound in air as 979 feet per second (298 m/s). This is too low by about 15%. The discrepancy is due primarily to neglecting the (then unknown) effect of rapidly fluctuating temperature in a sound wave (in modern terms, sound wave compression and expansion of air is an adiabati...
The transmission of sound can be illustrated by using a model consisting of an array of spherical objects interconnected by springs. In real material terms, the spheres represent the material's molecules and the springs represent the bondsbetween them. Sound passes through the system by compressing and expanding the springs, transmitting the acoust...
The speed of sound in mathematical notation is conventionally represented by c, from the Latin celeritasmeaning "swiftness". For fluids in general, the speed of sound cis given by the Newton–Laplace equation: 1. K s {\displaystyle K_{s}} is a coefficient of stiffness, the isentropic bulk modulus(or the modulus of bulk elasticity for gases); 2. ρ {\...
The speed of sound is variable and depends on the properties of the substance through which the wave is travelling. In solids, the speed of transverse (or shear) waves depends on the shear deformation under shear stress (called the shear modulus), and the density of the medium. Longitudinal (or compression) waves in solids depend on the same two fa...
In the Earth's atmosphere, the chief factor affecting the speed of sound is the temperature. For a given ideal gas with constant heat capacity and composition, the speed of sound is dependent solely upon temperature; see § Detailsbelow. In such an ideal case, the effects of decreased density and decreased pressure of altitude cancel each other out,...
Speed of sound in ideal gases and air
For an ideal gas, K (the bulk modulus in equations above, equivalent to C, the coefficient of stiffness in solids) is given by 1. γ is the adiabatic index also known as the isentropic expansion factor. It is the ratio of the specific heat of a gas at constant pressure to that of a gas at constant volume (C p / C v {\displaystyle C_{p}/C_{v}} ) and arises because a classical sound wave induces an adiabatic compression, in which the heat of the compression does not have enough time to escape th...
Effects due to wind shear
The speed of sound varies with temperature. Since temperature and sound velocity normally decrease with increasing altitude, sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source. Wind shear of 4 m/(s · km) can produce refraction equal to a typical temperature lapse rate of 7.5 °C/km. Higher values of wind gradient will refract sound downward toward the surface in the downwind direction,eliminating the acoustic shadow on the...
Tables
In the standard atmosphere: 1. T0 is 273.15 K (= 0 °C = 32 °F), giving a theoretical value of 331.3 m/s (= 1086.9 ft/s = 1193 km/h = 741.1 mph = 644.0 kn). Values ranging from 331.3 to 331.6 m/smay be found in reference literature, however; 2. T20 is 293.15 K (= 20 °C = 68 °F), giving a value of 343.2 m/s (= 1126.0 ft/s = 1236 km/h = 767.8 mph = 667.2 kn); 3. T25 is 298.15 K (= 25 °C = 77 °F), giving a value of 346.1 m/s (= 1135.6 ft/s = 1246 km/h = 774.3 mph = 672.8 kn). In fact, assuming an...
General physical considerations
The medium in which a sound wave is travelling does not always respond adiabatically, and as a result, the speed of sound can vary with frequency. The limitations of the concept of speed of sound due to extreme attenuation are also of concern. The attenuation which exists at sea level for high frequencies applies to successively lower frequencies as atmospheric pressure decreases, or as the mean free path increases. For this reason, the concept of speed of sound (except for frequencies approa...
Practical application to air
By far, the most important factor influencing the speed of sound in air is temperature. The speed is proportional to the square root of the absolute temperature, giving an increase of about 0.6 m/sper degree Celsius. For this reason, the pitch of a musical wind instrument increases as its temperature increases. The speed of sound is raised by humidity. The difference between 0% and 100% humidity is about 1.5 m/sat standard pressure and temperature, but the size of the humidity effect increase...
Mach number, a useful quantity in aerodynamics, is the ratio of air speed to the local speed of sound. At altitude, for reasons explained, Mach number is a function of temperature.Aircraft flight instruments, however, operate using pressure differential to compute Mach number, not temperature. The assumption is that a particular pressure represents...
A range of different methods exist for the measurement of sound in air. The earliest reasonably accurate estimate of the speed of sound in air was made by William Derham and acknowledged by Isaac Newton. Derham had a telescope at the top of the tower of the Church of St Laurence in Upminster, England. On a calm day, a synchronized pocket watch woul...
William Shakespeare ( c. 23 [a] April 1564 – 23 April 1616) [b] was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. [4] [5] [6] He is often called England's national poet and the " Bard of Avon " (or simply "the Bard").
Signature. Michael Joseph Jackson (August 29, 1958 – June 25, 2009) was an American singer, songwriter, dancer, and philanthropist. Dubbed the " King of Pop ", he is regarded as one of the most significant cultural figures of the 20th century.
Adolf Hitler [a] (20 April 1889 – 30 April 1945) was an Austrian-born German politician who was the dictator of Nazi Germany from 1933 until his suicide in 1945. He rose to power as the leader of the Nazi Party, [c] becoming the chancellor in 1933 and then taking the title of Führer und Reichskanzler in 1934.
