9TH GRADE · MECHANICAL VIBRATIONS
Harmonic, damped and forced oscillations
Harmonic law, energy loss and resonance.
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Basic Concepts
Damped and forced oscillations
Damped oscillations lose amplitude due to resistance, while forced oscillations are supported by an external periodic force.
After the transition process, the forced system oscillates with the frequency of the external influence.
Harmonic vibrations
Oscillations in which the coordinate changes according to the law of sine or cosine with a constant frequency.
The phase specifies the state of the oscillatory system at a selected moment and allows you to compare several oscillations.
resonance
A sharp increase in the amplitude of forced oscillations when the external and natural frequencies are close.
Resonance is useful in musical instruments and radio engineering, but is dangerous for bridges and undamped machines.
Physical quantities
Phase
An argument of the harmonic law that specifies the state of oscillation.
Unit: radian ·
Cyclic frequency
The rate of change in the phase of harmonic oscillations.
Unit: radians per second ·
Lesson formulas
Harmonic law
The coordinate of the harmonic oscillator changes along a cosine with a given amplitude, frequency and phase.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.