Oscillations

Question 1

What is an oscillation?

Answer 1

The repetitive variation with time of the displacement of an object about the equilibrium position

Question 2

What is displacement (x)?

Answer 2

The distance of a point on the wave from its equilibrium position

Question 3

What is amplitude (x0)?

Answer 3

The maximum value of the displacement on either side of the equilibrium position

Question 4

What is the period (T)?

Answer 4

The time interval for one complete oscillation to occur

Question 5

What is frequency (F)?

Answer 5

The number of oscillations per second

Question 6

What is phase difference?

Answer 6

A measure of how much a point or a wave is in front or behind another

Question 7

What is angular frequency (ω)?

Answer 7

The rate of angular displacement with respect to time

Question 8

What are the main angular frequency equations?

Answer 8

ω = 2pi / T
ω = 2pi f

T = time period
f = frequency

Question 9

What is simple harmonic motion?

Answer 9

An oscillation where the acceleration of a body is proportional to its displacement but acts in the opposite direction

a ∝ - x

Question 10

What are the 3 conditions for simple harmonic motion?

Answer 10

• The acceleration is proportional to the displacement
• The acceleration is in the opposite direction to the displacement
• The acceleration is always directed towards the equilibrium position

Question 11

What is the simple harmonic motion equation?

Answer 11

a = -ω^2 x

a = acceleration
ω = angular frequency ( rad s^-1)
x = displacement

Question 12

What does an isochronous oscillation mean?

Answer 12

The period of the oscillation is independent of the amplitude

Question 13

What type of oscillations occur when an oscillator is in simple harmonic motion?

Answer 13

Isochronous oscillations

Question 14

How can you determine the period and frequency on SHM oscillations - using hanging masses?

Answer 14

Question 15

How can you determine the period and frequency on SHM oscillations - using a pendulum?

Answer 15

Question 16

What equation is used to find the position of an object in SHM when the object began oscillating at the equilibrium position?

Answer 16

x = A sin ωt

Question 17

What equation is used to find the position of an object in SHM when the object began oscillating at the amplitude position?

Answer 17

x = A cos ωt

Question 18

When does the maximum velocity of an oscillator occur?

Answer 18

At the equilibrium position

Question 19

What is the velocity, angular frequency, amplitude and displacement equation?

Answer 19

where x0 = amplitude

Question 20

What are the maximum velocity equations?

Answer 20

v = v0 cos ω
v0 = ωA

where v0 is maximum velocity

Question 21

What is the SHM displacement-time graph?

Answer 21

Question 22

What is the SHM velocity-time graph?

Answer 22

Question 23

What is the SHM acceleration-time graph?

Answer 23

Question 24

What is energy constantly changing between for simple harmonic motion?

Answer 24

Between kinetic and potential energies

Question 25

What is the potential energy type for a pendulum?

Answer 25

Gravitational potential energy

Question 26

What is the potential energy type for a horizontal mass on a spring?

Answer 26

Elastic potential energy

Question 27

When is the KE at a maximum in SHM?

Answer 27

When the displacement equals 0 - equilibrium position

Question 28

Why is KE maximum at the equilibrium position?

Answer 28

Because velocity is maximum at equilibrium and KE = 1/2 mv^2

Question 29

When is KE zero during SHM?

Answer 29

At amplitude position

Question 30

When is potential energy at a maximum during SHM?

Answer 30

When the oscillator is at amplitude position

Question 31

What does the total energy of a simple harmonic system do?

Answer 31

Stays constant during oscillations - its constantly exchanges between kinetic and potential energies, when one increases the other decreases and vice versa

Question 32

What is the energy of a SHM oscillator equation?

Answer 32

E = 1/2 m ω^2 A^2 E = total energy of a simple harmonic system m = mass of oscillator (kg) ω = angular frequency (rad/s) A = amplitude (m)

Question 33

What does the graph for energy against displacement look like for a simple harmonic system?

Answer 33

Question 34

What is a free oscillation?

Answer 34

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

Question 35

What is a free vibration?

Answer 35

A vibration that always oscillates at its resonant frequency

Question 36

What is a forced oscillation?

Answer 36

Oscillations that are acted on by a periodic external force where energy is given in order to sustain oscillations

Question 37

Why do all systems eventually stop oscillating?

Answer 37

Because of resistive forces - such as friction or air resistance - that act in the opposite direction to the motion of oscillations

Question 38

What is damping?

Answer 38

The reduction in energy and amplitude of oscillations due to resistive forces on the oscillating system

Question 39

How long does damping have an effect for?

Answer 39

Until the oscillator comes to a stop

Question 40

What does not change when an oscillating system becomes damped?

Answer 40

The frequency - it remains the same with the decreasing amplitude

Question 41

What is light damping?

Answer 41

Damping that causes the amplitude to decrease gradually - it decays exponentially with time

Question 42

What is critical damping?

Answer 42

Damping that when displaced the oscillator will return to rest at its equilibrium position in the shortest possible time without oscillating

Question 43

What is heavy damping?

Answer 43

Damping that when displaced, the oscillator will take a long time to return to its equilibrium position with without oscillating

Question 44

What types of damping occur with no more oscillations happening?

Answer 44

Critical & heavy

Question 45

What is a driving frequency?

Answer 45

The frequency of forced oscillations

Question 46

What is natural frequency?

Answer 46

The frequency of an oscillation when the system is allowed to oscillate freely

Question 47

What is resonance?

Answer 47

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

Question 48

What does resonance look like graphically?

Answer 48

Question 49

What reduces the amplitude of resonance vibrations?

Answer 49

Damping

Question 50

What does different levels of damping when resonance occurs look like graphically?

Answer 50

Question 51

What are the purposes of resonance?

Answer 51

- In an organ pipe - the air molecules resonate to an increase in amplitude of sound - Radio receivers - the resonance of the radio waves allows the signal to be amplified by the receiver to listen - Microwave oven