07 Mechanical Waves

Question 1

What is a progressive wave?

Answer 1

Transfers energy from one place to another without transferring matter.

Question 2

What is the definition of wave speed?

Answer 2

The distance travelled by a wave front per unit time.

Question 3

If uncertainties are to be added or subtracted, what should you do?

Answer 3

Add the uncertainties

Question 4

If uncertainties are to be multiplied or divided, what should you do?

Answer 4

Add the percentage uncertainties

Question 5

If an uncertainty is to raised to a power, what should you do?

Answer 5

Multiply the percentage uncertainty by that power.

Question 6

What must you do in order to produce a continuous wave on a slinky?

Answer 6

One end of the slinky must be continuously moved from side to side.

Question 7

What happens in one cycle of vibration?

Answer 7

One point in the medium oscillates from it’s equallibrium position to one extreme to the other extreme and back to the equilibrium position.

Question 8

What is a transverse wave?

Answer 8

A wave where the oscillations are perpendicular to the direction of propagation.

Question 9

What is the direction of propagation also known as?

Answer 9

The direction of energy transfer.

Question 10

Where is the peak of a transverse wave?

Answer 10

The highest point

Question 11

What is the peak of a wave also known as?

Answer 11

The creast

Question 12

Where is the trough on a transverse wave?

Answer 12

The lowest point on a wave

Question 13

What is a longitudinal wave?

Answer 13

A wave where the oscillations are parallel to the direction of the propagation.

Question 14

Where is the compression on a longitudinal wave?

Answer 14

A region where the turns are close together.

Question 15

Where is the rarefaction on a longitudinal wave?

Answer 15

A region where the turns are far apart than position.

Question 16

What type of wave is a microwave?

Answer 16

Transverse

Question 17

What type of wave is a sound wave?

Answer 17

Longitudinal

Question 18

What type of wave is a red light?

Answer 18

Transverse

Question 19

What type of wave is a P wave?

Answer 19

Longitudinal

Question 20

What type of wave is a radio wave?

Answer 20

Transverse

Question 21

What type of wave is a gamma wave?

Answer 21

Transverse

Question 22

What type of wave is an infra red wave?

Answer 22

Transverse

Question 23

What type of wave is an x-ray?

Answer 23

Transverse

Question 24

What type of wave is an S wave?

Answer 24

Transverse

Question 25

Which waves are caused by an earthquake?

Answer 25

•P waves •S waves

Question 26

What is the symbol for displacement in waves?

Answer 26

x

Question 27

What is the displacement (x) of a point in the medium?

Answer 27

It's distance and direction from it's equilibrium position

Question 28

What is a frequency of a vibration?

Answer 28

The number of cycles of vibration in 1 second.

Question 29

What is frequency measured in?

Answer 29

Hertz (Hz)

Question 30

In waves, what is the symbol for the time period?

Answer 30

T

Question 31

What is the time period (T) of a wave?

Answer 31

The time for 1 cycle of vibration

Question 32

What does a mechanical wave require?

Answer 32

A substance to travel through

Question 33

What is the material that carries a mechanical wave called?

Answer 33

The medium

Question 34

What does an 'in phase' describe?

Answer 34

2 points in the medium that are moving in the same direction and change direction at the same instant.

Question 35

What is a wavelength (λ)?

Answer 35

The distance between 2 consecutive points that are in phase.

Question 36

What is the amplitude of a wave?

Answer 36

The maximum displacement of a vibrating point in the medium from the mean position.

Question 37

What is the mean position of a wave?

Answer 37

The rest position

Question 38

What is the phase difference of a wave?

Answer 38

The amount by which one vibration lags behind another

Question 39

What is phase difference measured in?

Answer 39

Degrees (°)

Question 40

If one point on a wave lags another by 1/2 cycle of vibration, what is the phase difference?

Answer 40

180 ° (or π) (or antiphase) *fractions allowed*

Question 41

If one point on a wave lags another by 1/4 cycle of vibration, then what is the phase difference?

Answer 41

90° (or ½π)

Question 42

What is the symbol for wave speed?

Answer 42

c

Question 43

What is diffraction? (Waves)

Answer 43

The bending of waves as they pass through a gap or pass by an obstacle.

Question 44

When does maximum diffraction (waves) happen?

Answer 44

When the gap is a similar size to the wavelength.

Question 45

What is superposition in waves?

Answer 45

When two or more waves meet at a point.

Question 46

What is constructive interference in waves?

Answer 46

It causes a large amplitude and occurs when waves arrive at a point in phase.

Question 47

What is disruptive interference in waves?

Answer 47

Produces zero amplitude and occurs at a point when two waves arrive 180° out of phase.

Question 48

What is a coherent sources of waves?

Answer 48

Sources which have the same frequency and have **constant phase angle**.

Question 49

Do coherent waves produce an interference pattern?

Answer 49

Yes

Question 50

Do non coherent waves produce an interference pattern?

Answer 50

No

Question 51

When a crest superposes with a crest what is produced? What is it called?

Answer 51

A larger crest. Constructive interference

Question 52

When a trough superposes with a trough, what is produced? What is it called?

Answer 52

A larger trough. Constructive interference

Question 53

When a crest superposes with a trough what do they do? What is it called?

Answer 53

They cancel each other out. Destructive interference.

Question 54

What is this?

Answer 54

A wave pattern produced by two dippers.

Question 55

What is this wave pattern described as?

Answer 55

A series of interference fringes.

Question 56

When two waves undergo superposition, what is the total displacement the sum of?

Answer 56

The displacements due to the individual waves.

Question 57

What is the path difference in waves?

Answer 57

The extra distance travelled by the wave from one source compared with the wave from the other source.

Question 58

In which terms should path difference be written in?

Answer 58

In terms of wavelength.

Question 59

If the path difference is nλ what type of interference is it?

Answer 59

Constructive interference

Question 60

If the path difference is (n+1/2)λ what type of interference is it?

Answer 60

Destructive interference

Question 61

What is a node in stationary waves?

Answer 61

A point which always has zero amplitude (and zero energy). The superposition of the incident and reflected waves produces destructive interference.

Question 62

How much is a node to node separation?

Answer 62

1/2 λ

Question 63

What is an antinode on a stationary wave?

Answer 63

A point which has the maximum amplitude (and maximum energy). The superposition of the incident and reflected waves causes constructive interference.

Question 64

What is an easy way to remember a node (stationary wave)? Node=...

Answer 64

Node=no displacement

Question 65

What is an easy way to remember antinode (stationary wave)? Antinode=...

Answer 65

Antinode=maximum displacement

Question 66

What does the vibration of a string give an appearance of?

Answer 66

'Loops'

Question 67

Why does the vibration of string give the appearance of 'loops'?

Answer 67

Due to 'the persistence of vision'.

Question 68

Within one 'loop' of the vibration of string, how does everything vibrate?

Answer 68

In phase

Question 69

Show this string ¼ later

Answer 69

Question 70

What are the conditions necessary to produce a stationary wave?

Answer 70

Question 71

What does µ stand for in melde's equation?

Answer 71

Mass per unit length

Question 72

What must you be careful of in waves equations (T)?

Answer 72

Capital T stands for both Time and Tension.

Question 73

What is the phase difference between a neighbouring crest and trough?

Answer 73

π