Mechanical Waves Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What 3 things do we need to consider to derive the equation of motion for mechanical waves in a gas?

A
  1. The gas moves and changes the density.
  2. The change in density corresponds to a change in pressure
  3. The change in pressure generates motion.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How is the change in pressure related to the density?

A

Change in pressure in proportional to change in density.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does the displacement relate to the change in density?

A

dϱ/P0 = -du/dx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What two values of pressure do we need to calculate the force of the wave?

A

Pressure at x minus pressure at x+dx = -dp/dx Δx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the value of mass times acceleration for gas in a volume?

A

mass: ϱ0*Δx
acceleration: d^2 u/dt^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the wave equation including Κ?

A

1/Κ * d^2 u/dt^2 = d^ u/dx^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the bulk modulus of a gas?

A

B = -pressure change/fractional volume change = -V dp/dv = + ϱ dp/dϱ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the equation for wave velocity in terms of bulk modulus?

A

v = sqrt(B/ϱ)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the wave equation in terms of the bulk modulus?

A

ϱ/B * d^2 u/dt^2 = d^2 u/dx^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the equation for elastic modulus?

A

elastic modulus = stress/strain = force per unit area/fraction displacement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the equation for wave speed in terms of the youngs modulus?

A

v = sqrt(Y/ϱ)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly