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Questions 505 A transverse wave is one in which the elements of the medium move in a direction perpendicular to the direction of propagation. An example is a wave on a taut string. A Any one-dimensional wave traveling with a speed v in the x direction can be repre- sented by a wave function of the form y(x, t) ! f(x * vt) (16.1, 16.2) where the positive sign applies to a wave traveling in the negative x direction and the The wave function for a one-dimensional sinusoidal wave traveling to the right can be expressed as (16.5, 16.10) where A is the amplitude, % is the wavelength, k is the angular wave number, and ' is the angular frequency. If T is the period and f the frequency, v, k, and ' can be written (16.6, 16.12) (16.8) (16.3, 16.9) The speed of a wave traveling on a taut string of mass per unit length + and tension T is (16.18) A wave is totally or partially reflected when it reaches the end of the medium in which it propagates or when it reaches a boundary where its speed changes discontinu- The power transmitted by a sinusoidal wave on a stretched string is (16.21) Wave functions are solutions to a differential equation called the linear wave equation: (16.27) ) 2 y ) x 2 ! 1 v 2
) 2 y ) t 2 " ! 1 2 +' 2 A 2 v v ! √ T '
% 2& T ! 2&f k % 2& % v ! % T ! % f y ! A sin ! 2& %
(x " vt) " ! A sin(kx " 't) S U M M A R Y Take a practice test for this chapter by clicking on 1. Why is a pulse on a string considered to be transverse? How would you create a longitudinal wave in a stretched 3. By what factor would you have to multiply the tension in a stretched string in order to double the wave speed? 4. When traveling on a taut string, does a pulse always invert upon reflection? Explain. 2. 5. Does the vertical speed of a segment of a horizontal taut string, through which a wave is traveling, depend on the 6. If you shake one end of a taut rope steadily three times each second, what would be the period of the sinusoidal 7. Q U E S T I O N S |