The simple harmonic motion of the masses is damped by the cardboard disc. The amount of damping increasing with the area of the disc.
The amplitude of the motion (A) decreases exponentially with time (t) following the equation:
A = Aoe-kt where Ao is the original amplitude and k is the damping constant. A large value of k gives greater damping.
Damped oscillations are oscillations where energy is taken from the system and so the amplitude decays. They may be of two types:
(i) Natural damping, examples of which are:
internal forces in a spring,
fluids exerting a viscous drag.
(ii) Artificial damping, examples of which are:
electromagnetic damping in galvanoŽmeters, the coating of panels in cars to reduce vibrations, shock absorbers in cars, interference damping - gun mountings on ships.