A longitudinal wave travels on a slinky or any long spring. The wave is represented by the equation z(z, t) = 1.2 cm cos(1800 rad/s t + 60 m⁻¹ z). What are the wavenumber and direction of propagation of the wave? A) 60 m⁻¹; traveling in the + z direction B) 60 m⁻¹; traveling in the − z direction C) 60 m⁻¹; traveling in the + x direction D) 60 m⁻¹; traveling in the − x direction

Question

Quizplus · Accepted Answer

The wavenumber is given by the coefficient in front of z in the argument of the cosine function, which is 60 m⁻¹. Since this coefficient is negative, the wave is traveling in the − z direction.

A Longitudinal Wave Travels on a Slinky or Any Long