Copy of Harmonic Series and Standing Waves on a String

Instructions
This simulation shows a wave on a string. The driving frequency and tension (via hanging mass) can be adjusted. Certain frequencies result in standing waves. Click the play button in the bottom left corner to see how the string vibrates.
[list=1][*]Try to find a few standing waves by adjusting frequency (the arrow keys on a keyboard can be used for fine control). Is there a pattern to the frequencies?[/*][*]What effect does changing the hanging mass have?[/*][*]The total amplitude of the wave is plotted. What does amplitude depend on? When is it largest?[/*][*]What settings result in a standing wave with the greatest number of nodes?[/*][/list]

Information: Copy of Harmonic Series and Standing Waves on a String