A simple java applet that illustrates the topic of normal modes of oscillation. The applet displays the motion of identical air track gliders attached to each other and the ends of the air track by identical springs. The user can adjust the number of gliders (from 1 to 7 in the full applet, fixed at 3 in the free demo) and can graphically adjust the initial positions of the gliders. A frequency graph records the weight of each normal mode in the oscillations, and can be used to select a single mode. The simulation illustrates the symmetric, antisymmetric, and group normal modes for a simple system.
Understanding of coupled oscillators and normal modes.
Target Student Population:
Junior or Introductory level Mechanics class with some guidance
Prerequisite Knowledge or Skills:
For effective use of this material, students will need an introduction to oscillations and normal modes.
Evaluation and Observation
Including frequency information about the oscillators is very useful and enlightening. The ability to click on a normal mode in the frequency spectrum to investigate its motion is excellent.
The frequency graph in the applet suggests that even complicated motions can be decomposed as a set of overlapping periodic motions.
The applet would be much more useful if it included the ability to change the masses and spring constants.
Potential Effectiveness as a Teaching Tool
Recommended Use(s) for Material: Independent study by students and Demonstrations
The display of both the position and frequency information on the same screen gives students a good picture of the physics of normal modes. This gives students an immediate impression of how changing the mass positions mixes the modes.
The inability to change masses and spring constants limits the use of this applet.
Ease of Use for Both Students and Faculty
This applet is very well designed and easy to use.