Chapter 16: Waves I

Question 1

Mechanical waves can be described as…

Answer 1

Extended disturbances of a medium that contain energy.

Question 2

What are traveling waves?

Answer 2

Waves in which the energy associated with the wave propagates through the medium.

Question 3

What are transverse traveling waves?

Answer 3

Waves in which the disturbance of the medium is perpendicular to the direction the wave travels.

Question 4

What are longitudinal traveling waves?

Answer 4

Waves in which the disturbance of the medium is parallel to the direction the wave travels.

Question 5

What are standing waves?

Answer 5

Waves in which the energy associated with the wave does not propagate through the medium.

Question 6

Sinusoidal transverse traveling waves occur on a string when…

Answer 6

One end of the string moves in the y direction with simple harmonic motion.

Question 7

What wave function describes a transverse sinusoidal traveling wave?

Answer 7

y(x,t) = y(subm)sin(kx - ωt + ϕ)

Question 8

Transverse sinusoidal traveling waves travel in the ___ direction, while the medium itself oscillates parallel to the ___ direction.

Answer 8

x; y.

Question 9

What is amplitude (y(subm))?

Answer 9

The maximum displacement from equilibrium.
SI unit: m

Question 10

Angular frequency, ω, equals ___ and has SI unit ___.

Answer 10

2πf, 2π/T, or kv; rad/s.

Question 11

Angular wave number, k, equals ___ and has SI unit ___.

Answer 11

w/v, 2π/λ; rad/m.

Question 12

What is wavelength, λ?

Answer 12

The shortest repeat distance of the wave. λ = 2π/k.
SI unit: m

Question 13

What is the SI unit of phase angle, ϕ?

Answer 13

radians.

Question 14

In a uniform string under tension carrying a transverse sinusoidal traveling wave, v (is)/(is not) constant everywhere along the wave. The vector points (towards)/(away from) the direction the wave travels.

Answer 14

Is; towards.

Question 15

Each small segment of a string carrying a transverse sinusoidal traveling wave moves (parallel)/(perpendicular) to v. The speed of each segment (is)/(is not) constant.

Answer 15

Perpendicular; is not.

Question 16

What is transverse velocity?

Answer 16

The velocity of the medium as it travels perpendicular to the wave’s velocity.

Question 17

How do you calculate transverse velocity?

Answer 17

You take the partial derivative of y(x,t), treating x as a constant.

Question 18

The frequency of the wave’s determines the ___ of the resulting wave.

Answer 18

Frequency.

Question 19

The speed of a wave is determined by the ___ of the medium.

Answer 19

Properties.

Question 20

For a wave on a taut string, the speed is determined by…

Answer 20

the square root of tension over the linear mass density of the string (μ).

Question 21

The average power of a traveling wave is…

Answer 21

p(subavg) = 0.5μv(ω^2)(y(subm)^2)

Question 22

What is the law of superposition?

Answer 22

The law that states the net wave observed on a string to be the algebraic sum of the two individual waves.

Question 23

The sum of two waves traveling in the same direction is a sinusoidal (traveling)/(standing) wave with (the same)/(a different) angular frequency as/than the originals.

Answer 23

Traveling; the same.

Question 24

What is fully constructive interference?

Answer 24

Interference in which the phase difference Δϕ = 0 (meaning they are perfectly in phase), and the highest possible amplitude is achieved.

Question 25

What is fully destructive interference?

Answer 25

Interference in which the two waves are perfectly out of phase, and the amplitude is equal to zero.

Question 26

When two identical sinusoidal waves travel on the same medium in opposite directions, they create a…

Answer 26

Standing wave.

Question 27

In an equation of the form y(x,t), the amplitude is ALWAYS…

Answer 27

Whatever is outside of and multiplied against the sine in the equation.

Question 28

The maximum amplitude of a standing wave is called a(n) ___, and occurs at kx(suban) = ___.

Answer 28

Antinode; π/2, 3π/2, 5π/2…

Question 29

The minimum amplitude of a standing wave is called a(n) ___, and occurs at kx(n) = ___.

Answer 29

Node; π, 2π, 3π…

Question 30

Describe the n-th harmonic.

Answer 30

λ = 2L/n
f(subn) = v/(λ(subn)) = n(v/2L) = nf(sub1)