In each of the following examples, friction losses are sufficient to damp out the motion in about 4 to 8 cycles. Air tracks run for many more cycles, but are bigger and noisier.
To demonstrate a simple spring-mass system, one mass cart is centered on the track. A spring is connected to each end of the track and stretched to the bumper at the respective ends o f the track. The period of this system is on the order of several seconds. Using the black steel bars the cart's mass can be doubled, tripled, etc. The effect of mass on period is obvious, and can be quantified with a stopwatch.
If two carts are connected to the end stops using three springs, a coupled oscillator is produced. Translation, vibration, and energy swapping can all be shown.
Click on either image to see a movie.