Damping

• Free oscillations occur when an oscillatory system, such as a mass on a spring or a pendulum, is displaced and released with no resistive forces.
• The frequency of the free oscillations is referred to as the system’s natural frequency.
• In practice, there are resistive forces acting on an oscillating mass on a spring or a pendulum, such as air resistance.
• This causes the amplitude of the oscillation to decrease gradually, a process known as damping.
• The gradual decrease in amplitude is known as light-damping.
• The period of the oscillation does not change in light-damping.
• Heavy damping occurs when the resistive forces are significantly greater, making it difficult for the oscillating system to complete one cycle.
• Swinging doors are often designed with heavy damping to ensure that the door will swing shut without swinging too far beyond the equilibrium position.
• Heavy damping is used extensively in engineering such as for suspension systems, anti-recoil mechanisms and robotics.
• Overdamping occurs when the resistive forces are such that the system takes a long time to return to its equilibrium position.
• Overdamping is used in earthquake protection, door closing mechanisms and car boot opening systems.