Sound and Doppler Effect

Question 1

What is the speed of sound through air?

Answer 1

340 m/s

Question 2

Compare the velocity of sound in solids, liquids, gases.

Answer 2

Vsolid > v liquid > v gas

Question 3

Explain how sound works

Answer 3

Sound waves arise from longitudinal collisions between molecules around it. The more likely the molecules collide, then the more likely sound will be produced.

Question 4

Relate molecular weight and speed of molecules

Answer 4

The heavier the molecule, then the slower it will travel.

Question 5

Relate intermolecular forces and speed of molecules

Answer 5

The greater the intermolecular forces, then it will move faster to it’s normal position.

Question 6

What range can humans process sound?

Answer 6

20 to 20,000 Hz.

Question 7

Relate pitch and frequency

Answer 7

The higher the pitch, the higher the frequency.

The lower the pitch, the lower the frequency.

Question 8

What is intensity?

Answer 8

Intensity is related to how loud the sound is. Intensity is related the the amplitude of the wave. Large amplitude means, high intensity, and more loud.

Question 9

Equation for Intensity

Answer 9

Power / Area. Watts/ meters squared.

Question 10

What is the intensity reference

Answer 10

10^-12 to 1 w/m^2

Question 11

What is the shortcut for decibels

Answer 11

dB+10= 10(I)

Question 12

What is the formula for the doppler effect?

Answer 12

FL = FS ( V+/-VL) / (V+/- VS)

Question 13

Relate frequency and relative motion.

Answer 13

Frequency increases as the objects get close.

Frequency decreases as the objects go away.

Question 14

Contrast nodes and antinodes

Answer 14

Nodes don’t move

Antimodes have movement.

Question 15

What is the equation for frequency and wavelength for standing waves?

Answer 15

Frequency is: nv/ 2L
Wavelength is: 2L / n

velocity just depends on the type of string.

Question 16

How do you calculate the fundamental frequency ?

Answer 16

Subtract two consecutive harmonics.

Question 17

How do you calculate beat frequency?

Answer 17

Subtract two beats. Take the absolute value.

Question 18

What is the equation for frequency and wavelength for open pipes?

Answer 18

L = wavelength/ 2 
frequency = v/ 2L

Question 19

What is the equation for frequency and wavelength for closed pipe?

Answer 19

Frequency = nv/ 4L

Question 20

Most important equation for waves

Answer 20

velocity = frequency (wavelength)

Question 21

Describe speed of gases in different types of temperatures.

Answer 21

Speed of gases travels faster in warmer conditions.

Question 22

Relate wavelength, frequency, and changing mediums

Answer 22

When sound goes from one medium to another, the frequency stays the same however the velocity and the wavelength change.

Question 23

Relate velocity and sound wave frequency when traveling through a medium.

Answer 23

The velocity in a give medium is always the same regardless of the frequency.

Question 24

What is the formula for intensity of a sound wave?

Answer 24

Intensity is power / area. Area is 4 PI r^4

Question 25

Relate objects moving in the same direction with frequency

Answer 25

Objects moving in the same direction and speed the frequency cancels out.