- #1

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- 3

## Homework Statement

The displacement of particles in a string stretched in the x direction is represented by y. Which of the following expressions for y describe wave motion:

1: cos kx sin wt

2:[tex]k^2x^2-w^2t^2[/tex]

3:[tex]cos^2(kx+wt)[/tex]

## Homework Equations

Equation of a progressive wave is of the form [tex]y=f(t-\frac{x}{v})[/tex]

## The Attempt at a Solution

The first equation represents a standing wave. The second obviously can't be it (its not of the form f(t-x/v) ). But I thought the third one would represent the equation of a progressive wave. It doesn't though. Why?