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Drag (physics) In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.[1] This can exist between two fluid layers (or surfaces) or a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, drag forces depend on velocity.[2][3] Drag force is proportional to the velocity for a laminar flow and the squared velocity for a turbulent flow [...More...]  "Drag (physics)" on: Wikipedia Yahoo 

Stokes' Drag In 1851, George Gabriel Stokes George Gabriel Stokes derived an expression, now known as Stokes's law, for the frictional force – also called drag force – exerted on spherical objects with very small Reynolds numbers in a viscous fluid [...More...]  "Stokes' Drag" on: Wikipedia Yahoo 

Lifting Body A lifting body is a fixedwing aircraft or spacecraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing. Whereas a flying wing seeks to maximize cruise efficiency at subsonic speeds by eliminating nonlifting surfaces, lifting bodies generally minimize the drag and structure of a wing for subsonic, supersonic and hypersonic flight, or spacecraft reentry. All of these flight regimes pose challenges for proper flight safety. Lifting bodies were a major area of research in the 1960s and 70s as a means to build a small and lightweight manned spacecraft. The US built a number of lifting body rocket planes to test the concept, as well as several rocketlaunched reentry vehicles that were tested over the Pacific [...More...]  "Lifting Body" on: Wikipedia Yahoo 

Orthographic Projection Orthographic projection Orthographic projection (sometimes orthogonal projection), is a means of representing threedimensional objects in two dimensions. It is a form of parallel projection, in which all the projection lines are orthogonal to the projection plane,[1] resulting in every plane of the scene appearing in affine transformation on the viewing surface. The obverse of an orthographic projection is an oblique projection, which is a parallel projection in which the projection lines are not orthogonal to the projection plane. The term orthographic is sometimes reserved specifically for depictions of objects where the principal axes or planes of the object are also parallel with the projection plane,[1] but these are better known as multiview projections [...More...]  "Orthographic Projection" on: Wikipedia Yahoo 

Lord Rayleigh John William Strutt, 3rd Baron Rayleigh, OM, PC, PRS (/ˈreɪli/; 12 November 1842 – 30 June 1919) was a physicist who, with William Ramsay, discovered argon, an achievement for which he earned the Nobel Prize for Physics Physics in 1904. He also discovered the phenomenon now called Rayleigh scattering, which can be used to explain why the sky is blue, and predicted the existence of the surface waves now known as Rayleigh waves. Rayleigh's textbook, The Theory of Sound, is still referred to by acoustic engineers today. The Rayleigh number is named in his honour. It is a dimensionless number associated with natural convection.Contents1 Biography 2 Religious views 3 Honours and awards 4 Bibliography 5 See also 6 References 7 External linksBiography[edit] Strutt was born on 12 November 1842 at Langford Grove in Maldon, Essex [...More...]  "Lord Rayleigh" on: Wikipedia Yahoo 

Fluid In physics, a fluid is a substance that continually deforms (flows) under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas, and to some extent, plastic solids. Fluids are substances that have zero shear modulus, or, in simpler terms, a fluid is a substance which cannot resist any shear force applied to it. Although the term "fluid" includes both the liquid and gas phases, in common usage, "fluid" is often used as a synonym for "liquid", with no implication that gas could also be present. For example, "brake fluid" is hydraulic oil and will not perform its required incompressible function if there is gas in it. This colloquial usage of the term is also common in medicine and in nutrition ("take plenty of fluids"). Liquids form a free surface (that is, a surface not created by the container) while gases do not. The distinction between solids and fluid is not entirely obvious [...More...]  "Fluid" on: Wikipedia Yahoo 

NASA The National Aeronautics Aeronautics and Space Administration ( NASA NASA /ˈnæsə/) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program, as well as aeronautics and aerospace research.[note 1] President Dwight D. Eisenhower Dwight D. Eisenhower established NASA NASA in 1958[10] with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science [...More...]  "NASA" on: Wikipedia Yahoo 

Power (physics) In physics, power is the rate of doing work, the amount of energy transferred per unit time. Having no direction, it is a scalar quantity. In the International System of Units, the unit of power is the joule per second (J/s), known as the watt in honour of James Watt, the eighteenthcentury developer of the steam engine condenser. Another common and traditional measure is horsepower (comparing to the power of a horse). Being the rate of work, the equation for power can be written: power = work time displaystyle text power = frac text work text time The integral of power over time defines the work performed. Because this integral depends on the trajectory of the point of application of the force and torque, this calculation of work is said to be path dependent. As a physical concept, power requires both a change in the physical universe and a specified time in which the change occurs [...More...]  "Power (physics)" on: Wikipedia Yahoo 

Dimensionless Number In dimensional analysis, a dimensionless quantity is a quantity to which no physical dimension is applicable. It is also known as a bare number or a quantity of dimension one[1] and the corresponding unit of measurement in the SI is one (or 1) unit[2][3] and it is not explicitly shown. Dimensionless quantities are widely used in many fields, such as mathematics, physics, engineering, and economics [...More...]  "Dimensionless Number" on: Wikipedia Yahoo 

Horsepower Horsepower Horsepower (hp) is a unit of measurement of power (the rate at which work is done). There are many different standards and types of horsepower. Two common definitions being used today are the mechanical horsepower (or imperial horsepower), which is 745.7 watts, and the metric horsepower, which is approximately 735.5 watts. The term was adopted in the late 18th century by Scottish engineer James Watt Watt to compare the output of steam engines with the power of draft horses. It was later expanded to include the output power of other types of piston engines, as well as turbines, electric motors and other machinery.[1][2] The definition of the unit varied among geographical regions. Most countries now use the SI unit watt for measurement of power [...More...]  "Horsepower" on: Wikipedia Yahoo 

Cross Section (geometry) In geometry and science, a cross section is the nonempty intersection of a solid body in threedimensional space with a plane, or the analog in higherdimensional spaces. Cutting an object into slices creates many parallel cross sections [...More...]  "Cross Section (geometry)" on: Wikipedia Yahoo 

Density The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume:[1] ρ = m V displaystyle rho = frac m V where ρ is the density, m is the mass, and V is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume,[2] although this is scientifically inaccurate – this quantity is more specifically called specific weight. For a pure substance the density has the same numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging [...More...]  "Density" on: Wikipedia Yahoo 

Mechanical Work W = F ⋅ s W = τ θPart of a series of articles aboutClassical mechanics F → = m a → displaystyle vec F =m vec a Second Second law of motionHistory TimelineBranchesApplied Celestial Continuum Dynamics Kinematics Kinetics Statics StatisticalFundamentalsAcceleration Angular momentum Couple D'Alembert's principle Energykinetic potentialForce Frame of reference Inertial frame of reference Impulse Inertia / Moment of inertia MassMechanical power Mechanical w [...More...]  "Mechanical Work" on: Wikipedia Yahoo 

Reynolds Number The Reynolds number Reynolds number (Re) is an important dimensionless quantity in fluid mechanics used to help predict flow patterns in different fluid flow situations. At low Reynolds numbers flow tends to be dominated by laminar (sheetlike) flow, but at high Reynolds numbers turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow (eddy currents). These eddy currents begin to churn the flow, using up energy in the process, and for liquids increasing the chances of cavitation. Reynolds number Reynolds number has wide applications, ranging from liquid flow in a pipe to the passage of air over an aircraft wing. It is used to predict the transition from laminar to turbulent flow, and used in the scaling of similar but differentsized flow situations, such as between an aircraft model in a wind tunnel and the full size version [...More...]  "Reynolds Number" on: Wikipedia Yahoo 

Ocean Surface Wave In fluid dynamics, wind waves, or windgenerated waves, are surface waves that occur on the free surface of bodies of water (like oceans, seas, lakes, rivers, canals, puddles or ponds). They result from the wind blowing over an area of fluid surface. Waves in the oceans can travel thousands of miles before reaching land. Wind Wind waves on Earth range in size from small ripples, to waves over 100 ft (30 m) high.[1] When directly generated and affected by local winds, a wind wave system is called a wind sea. After the wind ceases to blow, wind waves are called swells. More generally, a swell consists of windgenerated waves that are not significantly affected by the local wind at that time [...More...]  "Ocean Surface Wave" on: Wikipedia Yahoo 

Speed Of Sound The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium. In dry air at 0 °C (32 °F), the speed of sound is 331.2 metres per second (1,087 ft/s; 1,192 km/h; 741 mph; 644 kn). At 20 °C (68 °F), the speed of sound is 343 metres per second (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or a kilometre in 2.91 s or a mile in 4.69 s. The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior. In common everyday speech, speed of sound refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: sound travels most slowly in gases; it travels faster in liquids; and faster still in solids [...More...]  "Speed Of Sound" on: Wikipedia Yahoo 