Discovered by the physicist Lionel Robert Wilberforce around 1896, the Wilberforce Pendulum is a coupled mechanical oscillator. When properly calibrated, the pendulum weight will initially move up and down, but the motion will then change until the weight is rotating, and there is no up and down motion at all. Then gradually the motion changes back to the up and down motion, and so on.
The up and down motion causes the spring to wind and unwind slightly, giving the mass a small rotation. Each oscillation causes the mass to rotate a little more, until the mass is undergoing purely rotational motion and no longer bobbing up and down. Thus the translational up and down energy slowly transfers to rotational energy.
Likewise, when the mass is rotating back and forth, the spring winds and unwinds. When it unwinds, the tension in the spring decreases and the mass drops as there is a smaller upward force pulling it up. Thus for each rotation it undergoes, the rotational energy starts to transfer back to translational energy, and the weight bobs up and down with greater amplitude, until it eventually transfers entirely back, and undergoes purely up and down motion. At this point the process repeats.
Adjustable Wilberforce Pendulum mass
5 inch helical harmonic spring
Mounting rod connected to a boss head clamp