Module 5 - 5.3.3 Damping

Question 1

Damping Forces (definition)

Answer 1

Reduce the amplitude of an oscillation with time, due to energy being removed from the oscillating system

Question 2

Natural Damping (definition)

Answer 2

Where damping occurs in oscillations due to the effect of air resistance or other frictional forces

Question 3

Artificial Damping (definition)

Answer 3

The process of deliberately reducing the amplitude of an oscillation

Question 4

Examples of Damping (3)

Answer 4

• a swing that will come to rest
• a piano string that will eventually stop vibrating
• the suspension system of a car (ensures amplitude of vibrations dies down quickly to not lead to discomfort for a person/damage to mechanism)

Question 5

As the damping forces increase (3)

Answer 5

• the rate at which energy is removed from the system increases
• this leads to a more noticeable reduction in amplitude
• the period of oscillation will increase slightly

Question 6

Natural Frequency (definition)

Answer 6

The frequency at which a system will oscillate when undergoing free oscillations

Question 7

Driving Frequency (definition)

Answer 7

The frequency of the driving force applied to an oscillating object

Question 8

Free Oscillations occur when

Answer 8

there is no external, periodic force

Question 9

When a forced oscillation is taking place (3)

Answer 9

• there is always at least 2 objects that are vibrating
• the object causing the vibration to happen (oscillated at driving frequency)
• the object being made to oscillate (oscillates at natural frequency)

Question 10

Resonance (definition)

Answer 10

• resonance in forced oscillations occurs when the driving frequency is equal to the natural frequency of the system being forced to oscillate
• results in the body oscillating at its natural frequency and maximum amplitude
• due to there being a maximum energy transfer

Question 11

Useful Application of Resonance (1)

Answer 11

microwave ovens

Question 12

Damaging Effect of Resonance (1)

Answer 12

bridges/buildings vibrating due to wind/earthquakes/traffic

Question 13

Barton’s Pendulum (2)

Answer 13

• as the heavy sphere swings backwards and forwards, energy is transferred along the sting to the other balls which will also start to swing
• since the length of the pendulum determines the natural frequency, the ball on the string of the same length as the driver frequency will perform oscillations with the greatest amplitude

Question 14

Increasing the amount of damping (2)

Answer 14

• reduces the amplitude of the driven oscillation
• slightly reduces the frequency that corresponds to the maximum amplitude of oscillation