Damped Harmonic Motion

Figure 101.

DAMPED HARMONIC MOTION

In reality, simple harmonic motion does not go on forever and guitar strings stop making sound; in the same way, a swing will stop swinging unless the child is pushed. Because of nonconservative forces and friction, the presence of completely undamped motion is rare.

With a small amount of damping, the period and frequency are nearly the same as for simple harmonic motion; however, the amplitude gradually decreases. This is because the force will remove energy from the system, usually in the form of thermal energy. The energy will cause a change in kinetic and potential energy of the system, so that the system eventually stops oscillating. Figure 102 shows damped oscillation.

Figure 102.