How much one wave lags behind another (radians, degrees or fraction of a cycle)
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What does a displacement time graph look like?
Displacement, x, varies as a cosine or sine graph with the maximum value of A (amplitude)
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What does a velocity time graph look like?
Velocity, v, is the gradient of the displacement time graph with the maximum value of (2pif)A (where f is the frequency of the oscillation)
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What does an acceleration time graph look like?
Acceleration, a, is the gradient of a velocity-time graph. It has a maximum value of (2pif)^2A
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What are forced Vibrations?
A periodic external driving force which causes a system to vibrate
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What is the frequency of a driving force called?
Driving frequency
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What is a free vibration?
Involves no transfer of energy from the oscillating object to surroundings, the object will oscillate at natural frequency at constant amplitude.
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What is the phase difference if the driving frequency much less than the natural frequency
The two are in phase (0 or 2pi)
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What is the phase difference if the driving frequency is higher than the natural frequency?
The two are out of phase/antiphase (pi or 180 degrees) because oscillator can’t keep up
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What is resonance?
Driving frequency approaches natural frequency. The system gains more and more energy from driving force so system vibrates with rapidly increasing amplitude.
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What is natural frequency?
Frequency which a system oscillates when there is no periodic driving force
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What is the phase difference at resonance?
90 degrees out of phase of pi/2 radians
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Examples of resonance
Radio tuned so electric circuit resonates at the same frequency as radio station, swing resonates if someone pushes at natural frequency
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What is light damping?
Takes long time to stop oscillating, small decrease in amplitude with every period
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What is heavy damping?
Takes less time to stop oscillating, amplitude gets much smaller each period
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What is critical damping?
Returns to the equilibrium in the fastest time.
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What effect does damping have on resonance peaks?
Light damping have sharp resonance peaks, becomes flatter as damping increases.
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What is Damping?
System loses energy to surroundings due to frictional forces. Causes a decrease in amplitude which eventually stops the oscillations.
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What is overdamping?
too much heavy damping which causes the system to take longer to return to the equilibrium
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Other cards in this set
Card 2
Front
What does a displacement time graph look like?
Back
Displacement, x, varies as a cosine or sine graph with the maximum value of A (amplitude)
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