Waves (Etkina 20)

Question 1

the object that causes the vibration

Answer 1

source

Question 2

short disturbance in surrounding medium

Answer 2

pulse

Question 3

the moving circular disturbance created by the source on water

Answer 3

wave front

Question 4

every point on the wave front has the same … at the same time

Answer 4

displacement from equilibrium

Question 5

longitudinal wave: the vibrational motion of the particles/layers of the medium is … to the direction of propagation of the disturbance

Answer 5

parallel

Question 6

transverse wave: the vibrational motion of the particles/layers of the medium is … to the direction of propagation of the disturbance

Answer 6

perpendicular

Question 7

when a wave encounters any boundary between different media, some of the wave is

Answer 7

reflected back

Question 8

sound is created by vibrations that cause … which travel through air from one place another

Answer 8

air pressure changes

Question 9

sound waves are

Answer 9

longitudinal

Question 10

period: … for one complete vibration of a … in the medium anywhere along the path

Answer 10

time period; point

Question 11

frequency: the number of … per second of a … in the medium as the wave passes

Answer 11

vibrations; point

Question 12

amplitude: the … of a … of the medium from its equilibrium position as the wave passes

Answer 12

maximum distance; point

Question 13

speed: the distance a … travels during a …, divided by that time interval

Answer 13

disturbance; time interval

Question 14

disturbance pattern of a wave repeats at a distance Tv, which separates neighboring locations on the wave that have the same displacement y and the same slope …

Answer 14

wavelength

Question 15

y (x,t) =

Answer 15

y(x,t) = Acos[2T(t/T-x/ lambda)]

Question 16

`2 points are in phase if at every clock reading their .. are exactly the same

Answer 16

displacements

Question 17

2 points separated by a distance equal to an integer multiple of … are always in phase

Answer 17

wavelengths

Question 18

the period and frequency of a wave depends on the

Answer 18

vibration source

Question 19

wave speed depends on the … and the …

Answer 19

medium; type of wave (pulse)

Question 20

… waves travel more slowly than … waves due to the types of … of the medium that occur when the waves propagate

Answer 20

transverse; longitudinal; deformation

Question 21

the energy per unit circumference length and per unit time crossing a line perpendicular to the direction that the wave travels decreases as …, where r is the distance from the … of the wave

Answer 21

1/4; point source

Question 22

the energy per unit area per unit time passing across the perpendicular to the direction that the wave travels decreases as …, where r is the distance from the point source of the wave

Answer 22

1/r^2

Question 23

intensity of a wave is the energy per unit area per time interval that crosses perpendicular to an area in the medium through which it travels. I =

Answer 23

delta U/ delta t * A = P/A

Question 24

reflected pulses are

Answer 24

inverted

Question 25

When a thin rope is connected with a thicker rope, and an upright transverse pulse is transmitted, a … is initiated in the thick rope at the boundary. But since the thick rope has a larger mass per unit length, it exerts a … force, starting an … pulse back toward the left in the thin rope.

Answer 25

small amplitude upward pulse; downward; inverted reflected

Question 26

When a thick rope is connected with a thinner rope, and an upright transverse pulse is transmitted, the small rope … its position relative to the thick rope and starts a small …pulse back in the thick rope due to its smaller mass per unit length.

Answer 26

overshoots; upright reflected

Question 27

impedance: the degree to which waves are … and … at the boundary between different media

Answer 27

reflected; transmitted

Question 28

impedance is the measure of the difficulty a wave has in … the medium, depends on the medium’s … and … properties

Answer 28

distorting; elastic; inelastic

Question 29

If two media connected together have different elastic and inertial properties, wave traveling in one medium is partially …and partially … at the boundary. If the product of the elastic and inertial properties of the two media is the same, a wave moves from one medium to the other as if there is no … If the impedances of two media are very different, most of the wave energy is reflected back into the first medium and does not …

Answer 29

reflected; transmitted; ; change; travel into the second medium

Question 30

When multiple waves pass through the same medium at the same time, the net displacement at a particular time and location in the medium is the …that would be caused by each wave if it were alone in the medium at that time. Mathematically, this statement can be written as …

Answer 30

sum of the displacements; ynet = y1 + y2 + …

Question 31

the process of two or more waves of the same frequency overlapping is called

Answer 31

interference

Question 32

constructive interference: places where the waves add to create a

Answer 32

larger disturbance

Question 33

destructive interference: places where two waves add to produce a

Answer 33

smaller disturbance

Question 34

the frequencies fn at which a string with fixed ends can vibrate are: fn =

Answer 34

nv/2L

Question 35

antinodes reach the … on a standing wave

Answer 35

maximum displacement

Question 36

nodes: points on a standing wave that do not … at all

Answer 36

vibrate

Question 37

points on a standing wave vibrate

Answer 37

in phase