Vibration and waves

Question 1

Simple harmonic motion

Answer 1

The to and fro vibratory motion (oscillatory motion) of a swinging pendulum in a small arc

Question 2

Sine curve

Answer 2

Pictorial representation of a wave

Question 3

Amplitude

Answer 3

Distance from the midpoint to the crest (or trough) of a wave

Question 4

Wavelength

Answer 4

Distance from the top of one crest to the top of the next one

Question 5

Frequency

Answer 5

How frequently a vibration occurs, number of to and fro vibrations it makes in a give time

Question 6

Hertz

Answer 6

Unit of frequency (one vibration per second is hertz)

Question 7

Period

Answer 7

Time for one complete vibration

Frequency = 1/period 
Period = 1/frequency

Question 8

Wave motion

Answer 8

• with wave motion, energy can be transferred from one source to a receiver without the transfer of matter between the two points

Question 9

Wave speed

Answer 9

• related to the frequency and wavelength of the waves
• speed = distance/time
• wave speed = wavelength / period
• since period = inverse of frequency,
  Wave speed = wavelength x frequency

Question 10

Transverse waves

Answer 10

• waves produced when the motion of the medium is transverse (or at right angle) to the direction the wave travels
• waves in the stretched stings of musical instruments, electromagnetic waves which make up radio and light waves

Question 11

Longitudinal waves

Answer 11

• motion along the direction of the wave rather than at right angles to it
• wavelength of a longitudinal wave is the distance between successive compression or the distance between successive rarefactions (stretched regions)
• slinky, sound waves, P waves of earthquake

Question 12

Interference

Answer 12

• when more than one wave occupies the same space at the same time
• when this occurs, the displacements add at every point (superposition principle)

Question 13

Constructive interference

Answer 13

When the crest of two or more waves overlap, and their individdual effects add together to produce a wave of increased amplitude

Question 14

Destructive interference

Answer 14

When the crest of one wave overlaps with the trough of another, their individual effects are reduced

Question 15

Standing waves

Answer 15

Where part of the object, called nodes, are stationary

Question 16

Nodes

Answer 16

Regions of minimal or zero displacement, with Manila or zero energy

Question 17

Antinodes

Answer 17

Regions fo maximum displacement and maximum energy

- occur halfway between nodes

Question 18

Standing waves cont.

Answer 18

• result of interference
• when two sets of waves of equal amplitude and wavelength pass through each other in opposite directions, the waves are steadily in and out of phase with each other