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In calculus, the trapezoidal rule (also known as the trapezoid rule or trapezium rule) [a] is a technique for numerical integration, i.e., approximating the definite integral: (). The trapezoidal rule works by approximating the region under the graph of the function f ( x ) {\displaystyle f(x)} as a trapezoid and calculating its area.
The phase velocity varies with frequency. The phase velocity is the rate at which the phase of the wave propagates in space. The group velocity is the rate at which the wave envelope, i.e. the changes in amplitude, propagates. The wave envelope is the profile of the wave amplitudes; all transverse displacements are bound by the envelope profile.
Oresme provided a geometrical verification for the generalized Merton rule, which we would express today as = (+) (i.e., distance traveled is equal to one half of the sum of the initial and final velocities, multiplied by the elapsed time ), by finding the area of a trapezoid. [3]
In fact, the region of absolute stability for the trapezoidal rule is precisely the left-half plane. This means that if the trapezoidal rule is applied to the linear test equation y' = λy, the numerical solution decays to zero if and only if the exact solution does. However, the decay of the numerical solution can be many orders of magnitude ...
Propagation of a wave packet demonstrating a phase velocity greater than the group velocity. This shows a wave with the group velocity and phase velocity going in different directions. The group velocity is positive, while the phase velocity is negative. [1] The phase velocity of a wave is the rate at which the wave propagates in any medium.
where is bulk density given in g/cm 3, is P-wave velocity given in ft/s, and and are empirically derived constants that depend on the geology. Gardner et al. proposed that one can obtain a good fit by taking α = 0.23 {\displaystyle \alpha =0.23} and β = 0.25 {\displaystyle \beta =0.25} . [ 1 ]
While a vertical velocity term is not present in the shallow-water equations, note that this velocity is not necessarily zero. This is an important distinction because, for example, the vertical velocity cannot be zero when the floor changes depth, and thus if it were zero only flat floors would be usable with the shallow-water equations.
Cross-sectional area distribution along the complete airframe determines wave drag, largely independent of the actual shape. The blue and light green shapes are roughly equal in area. The Whitcomb area rule , named after NACA engineer Richard Whitcomb and also called the transonic area rule , is a design procedure used to reduce an aircraft 's ...