what is the difference between harmonic motion and oscillatory motion?

Asked by Shunmathi Gs | 5th Dec, 2013, 09:42: PM

Expert Answer:

Oscillatory motion

  • Oscillations are a type of periodic motion. An oscillation is usually defined as a repetitive variation over time. The oscillation can occur over a middle equilibrium point or between two states.
  • A pendulum is a good example for an oscillatory motion. The oscillations are mostly sinusoidal. An alternating current is also a good example for oscillation. In the simple pendulum, the bob oscillates over the middle equilibrium point. In an alternating current, the electrons oscillate inside the closed circuit over an equilibrium point.
          There are three types of oscillatory motions
  • Un-damped oscillations:In which the internal energy of the oscillation remains a constant.
  • Damped oscillations: In the case the internal energy of the oscillation decreases over time.
  • Forced oscillations: force is applied on the pendulum in a periodic variation.

Simple Harmonic Motion

  • The simple harmonic motion is defined as a motion taking the form of a = – (ω2) x where “a” is the acceleration and “x” is the displacement from the equilibrium point. The term ω is a constant.
  •  A simple harmonic motion requires a restoring force. The restoring force can be a spring, gravitational force, magnetic force, or an electric force.
  •  A simple harmonic oscillation will not emit any energy. The total mechanical energy of the system is conserved. If the conservation does not apply, the system will be a damped harmonic system. A pendulum clock is the best example of simple harmonic systems.
  •  If external factors such as air resistance affect the motion, it will eventually dampen and will stop. A real life situation is always a damped oscillation.
  • At the equilibrium point, the kinetic energy of the system becomes a maximum, and at the turning point, the potential energy becomes a maximum and the kinetic energy becomes zero.
In short:
The simple harmonic motion is a special case of oscillatory motion, which is neither damped, nor driven and can be described by a sinusoidal function.

Answered by Komal Parmar | 6th Dec, 2013, 11:35: AM

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