physics
...nces that are in the same or opposite directions respectively. The speed of a mechanical wave is determined by a combination of elastic and inertial properties of the medium. For instance, a transverse wave on a taut string moves with a speed that is determined by the tension (the elastic property) and the linear mass density (the inertial property) of the string. When a wave encounters a change in the properties of the medium, it is partially (or totally) reflected and (possibly) partially transmitted. The disturbance in the reflected wave is in the opposite or same direction as that of the incident wave (i.e., inverted or not inverted respectively) according to whether the medium beyond the point of change is ˇ°less freeˇ± or ˇ°more freeˇ± (respectively) to vibrate. The disturbance in the transmitted wave is in the same direction as the incident wave and has an amplitude which is determined by how much the properties of the medium changed. In general, larger changes will produce smaller transmitted amplitudes. One very special type of nondispersive periodic wave is the sinusoidal wave. It is fully characterized by its amplitude, wavelength, and wave speed. Many equivalent mathematical forms for a sinusoidal wave can be written in terms of the various quantities which describe its spatial and temporal variations. The velocity and acceleration of a specific element of the medium (not to be confused with the motion of the wave itself) can be determined by taking derivatives of the dist...