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[Note: The Java Applet for this animation can no longer be run in a web browser. Clicking this link, however, will download to your computer a Java Web Start file named SimpleHarmonicMotionLaunch.jnlp. This file can launch the animation in a separate window on your computer. Downloading and executing the file may be blocked by local Java permissions, but persevere! You may finally have to launch the file by right-clicking (control-clicking) it and choosing Open, instead of simply double-clicking it.]
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This applet shows visually the relation between circular motion and simple harmonic motion. If a point travels in a circle at constant speed, then the projection of its position on a diameter of that circle moves with simple harmonic motion.
1. At the bottom of the window is a button labeled "Go/Stop." Clicking the button at any time stops or restarts the motion.
2. At the top of the window is a menu bar that controls the display. Available menu choices and their effects are the following:
| Menu Selection | Action |
|---|---|
| SHM > About SHM | Reveals the name of the author and the year the applet was written. |
| Image > Circle | Shows a point moving at constant speed around a circle. |
| Image > Diameter | Inserts a line along a vertical diameter of the circle. |
| Image > Projection | Adds a point on the diameter at the same height as the point moving in a circle. This point executes one-dimensional simple harmonic motion, a slow-motion representation of the motion of a mass oscillating at the end of an ideal spring. |
| Image > Graph | Imagine a red pen attached to the point moving along the diameter, marking paper moving leftward at constant speed. This produces a graph of the position of the point as a function of time. The graph is sinusoidal. |