The applet shows two waves and their superposition. While keeping the parameters for one wave the same, change the parameters for the other wave to create a standing wave. Note that you can't change the speed directly. Change the wavelength and frequency in order that both waves have the same speed.
Is there a cost for using this resource?
No
Are there copyright restrictions?
Yes
Physlets, that is, the applets themselves, may be used to author new problems and these problems may be distributed along with the Physlet jar files for non-profit, educational purposes without requesting permission under certain conditions.