A mechanical device to demonstrate the composition of two simple harmonic motions

Abstract

The slot link mechanism can project uniform rotation to a simple harmonic motion (SHM), based on which, the device including two sliding table systems has been prepared. These two sliding table systems can be stacked up and down, and each of them can produce a tunable mechanical SHM using a stepper motor. When the upper sliding table system is attached to the lower one and both are turned on, the motion of the sliding table of the upper component is the composition of the two SHMs. With the help of a self-powered LED, a violet laser, and a movable phosphorescent foil, this mechanical device can visualize the composition of the SHMs in the same and mutual perpendicular directions including the beat phenomenon and Lissajous figures. In addition to demonstrating several typical compositions of two SHMs, this device can also highlight the vector characteristics of mechanical vibration and demonstrate the tilted Lissajous figures.