Chapter 15 - Mechanical Waves

Question 1

What is a wave?

Answer 1

Any disturbance that propagates from one region to another.

Question 2

A mechanical wave travels within some material known as the

Answer 2

Medium

Question 3

Amplitude A is:

Answer 3

The maximum displacement of a particle in the medium.

Question 4

What is a sinusoidal wave?

Answer 4

A special periodic wave in which each point moves in SHM.

Question 5

The wave function y(x,t) describes:

Answer 5

The displacements on individual particles in the medium.

Question 6

Wave equation for a sinusoidal wave travelling in the +x direction

Answer 6

=Acos(omega(x/v - t))
=Acos2pi(x/lambda - t/T)
=Acos(kx-omegat)

Question 7

If a wave is moving in the -x direction, the wave equation changes how?

Answer 7

Minus signs become positive

Question 8

K =

Answer 8

2pi/lambda

Question 9

Omega

Answer 9

=2pif=vk

Question 10

The speed of transverse waves on a string depends on what?

Answer 10

Tension F and mass per unit length Inertia U

V= SQRT(F/u)

Question 11

Dy/dx y(x,t)

Answer 11

-kAsin(kx-omegat)

Slope

Question 12

D^2y/dx^2 y(x,t)

Answer 12

-k^2Acos(kx-omegat)

Curvature

Question 13

The wave equation:

Answer 13

Curvature= 1/v^2 d^2y(x,t)/dt^2

Question 14

U

Answer 14

M/L

Inertia

Question 15

Average power

Answer 15

= 0.5 SQRT(inertiaF)omega^2A^2

Question 16

For waves that spread out in R3 the wave intensity is inversely proportional to:

Answer 16

The square of the distance from the source.

I1/I2=r2^2/r1^2

Question 17

Principle of superposition:

Answer 17

Y(x,t) = y1(x,t) + y2(x,t)

Question 18

When a sinusoidal wave is reflected from a fixed or free end of a stretched string:

Answer 18

The incident and reflected waves combine to form a standing wave with nodes and antinodes.

Question 19

Adjacent nodes and antinodes are respectively spaced how far apart?

Answer 19

Lambda/2

Question 20

Y(x,t) for a standing wave on a string where x=0

Answer 20

(Asinkx)sin(omegat)

Question 21

fn=

Answer 21

n(v/2L)=nf1

Question 22

Fundamental frequency

Answer 22

1/2L SQRT(F/inertia)