Damping is the reduction in energy and amplitude of oscillations due to resistive forces on the oscillating system.

What causes the amplitude of a real oscillator to decrease over time?

Resistive forces (such as friction or air resistance), which act in the opposite direction to the motion (velocity) of the oscillator, causing damping.

What happens to the frequency of a damped oscillator as its amplitude decreases?

The frequency stays constant — it does not change as the amplitude decreases.

Describe how the amplitude of a lightly damped oscillator changes with time, and give an example.

The amplitude decreases exponentially with time while the oscillations continue, with the frequency remaining constant (for example, a swinging pendulum gradually decreasing in amplitude).

What is the difference between critical damping and heavy damping ?

Both return the oscillator to equilibrium without oscillating Critical damping does so in the shortest possible time (e.g. car suspension) Heavy damping takes longer than critical damping (e.g. a door damper)

A critically damped oscillator returns to its equilibrium position in the .......... possible time without oscillating.

A critically damped oscillator returns to its equilibrium position in the shortest possible time without oscillating.

True or False? A restoring force is what causes damping in an oscillating system.

False. A resistive force (not a restoring force) opposes the motion/velocity of the oscillator and causes damping; the restoring force is what brings the oscillator back to the equilibrium position.

Define a free oscillation .

An oscillation where there are only internal forces (no external forces) acting, and there is no energy input.

Define a forced oscillation .

An oscillation acted on by a periodic external (driving) force , where energy is given to the system in order to sustain the oscillations.

At what frequency does a free oscillation always vibrate?

Its own resonant (natural) frequency .

At what frequency are forced oscillations made to oscillate?

The same frequency as the external driving force producing them.

A periodic driving force does .......... against the resistive force in order to sustain forced oscillations.

A periodic driving force does work against the resistive force in order to sustain forced oscillations.

True or False? Striking a tuning fork and leaving it to vibrate is an example of a forced oscillation .

False. This is a free oscillation — after the initial strike, the tuning fork vibrates at its own natural frequency with no external driving force acting on it.

When the frequency of the applied (driving) force to an oscillating system is equal to its natural frequency , the amplitude of the resulting oscillations increases significantly.

Define the natural frequency of an oscillator.

The frequency at which an oscillating system oscillates when it is allowed to oscillate freely (with no driving force).

Describe how the amplitude of oscillations changes on a resonance curve as the driving frequency f increases from below the natural frequency f 0 to above it.

When f f 0 , amplitude decreases

Describe the effects of increasing damping on a resonance curve.

The amplitude of the resonance peak decreases The peak broadens The peak shifts slightly to the left of the natural frequency The natural frequency f 0 itself stays the same

A radio is tuned so that its electric circuit .......... at the same frequency as the broadcast being received.

A radio is tuned so that its electric circuit resonates at the same frequency as the broadcast being received.

Give two examples of resonance other than a tuned radio circuit.

An organ pipe, where air resonates down the air column to set up a stationary wave Glass smashing from a sound wave at the right (resonant) frequency

In Barton's pendulums , why does pendulum C (the same length L as driver X) have the largest amplitude?

Because its natural frequency is equal to the driving frequency of pendulum X.

True or False? In Barton's pendulums, the pendulums longer than L oscillate in phase with the driving pendulum X.

False. Pendulums longer than L (A and B) oscillate π out of phase with the driver; pendulums shorter than L (D and E) are in phase , and pendulum C (length L ) is 0.5π out of phase .

A LevelPhysicsAQAFlashcardsFurther Mechanics & Thermal PhysicsForced Vibrations & Resonance

Forced Vibrations & Resonance (AQA A Level Physics): Flashcards

Exam code: 7408

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FrontDamping
Define damping.

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Cards in this collection (21)

Define damping.
Damping is the reduction in energy and amplitude of oscillations due to resistive forces on the oscillating system.
What causes the amplitude of a real oscillator to decrease over time?
Resistive forces (such as friction or air resistance), which act in the opposite direction to the motion (velocity) of the oscillator, causing damping.
What happens to the frequency of a damped oscillator as its amplitude decreases?
The frequency stays constant — it does not change as the amplitude decreases.
Describe how the amplitude of a lightly damped oscillator changes with time, and give an example.
The amplitude decreases exponentially with time while the oscillations continue, with the frequency remaining constant (for example, a swinging pendulum gradually decreasing in amplitude).
What is the difference between critical damping and heavy damping?
- Both return the oscillator to equilibrium without oscillating
- Critical damping does so in the shortest possible time (e.g. car suspension)
- Heavy damping takes longer than critical damping (e.g. a door damper)
A critically damped oscillator returns to its equilibrium position in the .......... possible time without oscillating.
A critically damped oscillator returns to its equilibrium position in the shortest possible time without oscillating.
True or False?
A restoring force is what causes damping in an oscillating system.
False.
A resistive force (not a restoring force) opposes the motion/velocity of the oscillator and causes damping; the restoring force is what brings the oscillator back to the equilibrium position.
Define a free oscillation.
An oscillation where there are only internal forces (no external forces) acting, and there is no energy input.
Define a forced oscillation.
An oscillation acted on by a periodic external (driving) force, where energy is given to the system in order to sustain the oscillations.
At what frequency does a free oscillation always vibrate?
Its own resonant (natural) frequency.
At what frequency are forced oscillations made to oscillate?
The same frequency as the external driving force producing them.
A periodic driving force does .......... against the resistive force in order to sustain forced oscillations.
A periodic driving force does work against the resistive force in order to sustain forced oscillations.
True or False?
Striking a tuning fork and leaving it to vibrate is an example of a forced oscillation.
False.
This is a free oscillation — after the initial strike, the tuning fork vibrates at its own natural frequency with no external driving force acting on it.
Define resonance.
When the frequency of the applied (driving) force to an oscillating system is equal to its natural frequency, the amplitude of the resulting oscillations increases significantly.
Define the natural frequency of an oscillator.
The frequency at which an oscillating system oscillates when it is allowed to oscillate freely (with no driving force).
Describe how the amplitude of oscillations changes on a resonance curve as the driving frequency f increases from below the natural frequency f₀ to above it.
- When f < f₀, amplitude increases
- At f = f₀, amplitude is at its maximum (resonance)
- When f > f₀, amplitude decreases
Describe the effects of increasing damping on a resonance curve.
- The amplitude of the resonance peak decreases
- The peak broadens
- The peak shifts slightly to the left of the natural frequency
- The natural frequency f₀ itself stays the same
A radio is tuned so that its electric circuit .......... at the same frequency as the broadcast being received.
A radio is tuned so that its electric circuit resonates at the same frequency as the broadcast being received.
Give two examples of resonance other than a tuned radio circuit.
- An organ pipe, where air resonates down the air column to set up a stationary wave
- Glass smashing from a sound wave at the right (resonant) frequency
In Barton's pendulums, why does pendulum C (the same length L as driver X) have the largest amplitude?
Because its natural frequency is equal to the driving frequency of pendulum X.
True or False?
In Barton's pendulums, the pendulums longer than L oscillate in phase with the driving pendulum X.
False.
Pendulums longer than L (A and B) oscillate π out of phase with the driver; pendulums shorter than L (D and E) are in phase, and pendulum C (length L) is 0.5π out of phase.

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