This applet illustrates several factors that influence changes in wave frequency.
To try this
simulation:
Right-click and drag your mouse DOWN the applet to INCREASE the thickness of the red string or UP the applet to DECREASE the thickness. Left-click, hold, then release to pluck the string. The longer you hold, the greater the force from the string being plucked, and the greater the frequency.
What's Going On?
This applet simulates a string that is connected to the flexible bottom of a liquid-filled tank. As the string vibrates, the bottom vibrates and causes ripples on the surface of the fluid. As you tighten the string it vibrates faster. When you pluck the tight string, it springs back into position much quicker. If you loosen the string, the tension becomes less and the string has more freedom to flop around, so the frequency becomes less.
There's More!
You can try this at home. If you stretch a rubber band between two fingers and pluck it, you can hear it vibrate. If you stretch your fingers farther apart as you pluck the string, the frequency of the vibrations becomes higher as the tension on the rubber band becomes greater.
