Oscillations gradually die away. The amplitude decreases due to friction or air resistance reducing the total energy of the system. These forces are called dissipative forces as they dissipate the energy to the surroundings as heat. This is known as damping. The time period is independent of the amplitude and stays the same.
- Light damping: the amplitude decreases exponentially.
- Critical damping: after it has been displaced the system returns to its equilibrium position in the shortest possible time without overshooting.
- Heavy damping: the displaced object returns to its equilibrium position slowly. No oscillating occurs.