Oscillations and Waves Forced Oscillations and Resonance

Damping - Caused by resistive forces that always oppose motion e.g. friction -Energy is dissipated by these forces. E.g. friction or magnetic damping can result in kinetic energy being dissipated as heat energy flows from the system. - Damped systems do not describe SHM.

Degrees of damping - under damped: this means the body will oscillate before coming to rest at the equilibrium position. -critically damped: the body will come to rest at the equilibrium position in the shortest possible time, without oscillating. - over damped: this means the body will take longer to come to rest under critical over

Resonance Natural frequency: the frequency at which a body will freely oscillate at if plucked or banged or otherwise set in motion. Forced oscillations: these occur when a ‘driver’ oscillating body causes another body (the ‘driven’ body) to oscillate at the same frequency (not necessarily its natural frequency). Resonance: This occurs when the forced vibration frequency of the driver is equal to a driven objects natural frequency.

Resonance of a text book Physics

Resonance of a mass on a spring

E.g. The Tacoma narrows suspension bridge - Video clipVideo clip E.g. Breaking a wine glass using resonance -You tube clipYou tube clip

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