Chapter 7 Waves and Sound

Question 1

Transverse waves definition and examples

Answer 1

-waves in which the direction of particle oscillation is perpendicular to the movement (propagation) of the wave
“the wave” in crowds, electromagnetic waves like visible light, microwaves and x-rays
-particles are oscillating perpendicular to the direction of energy transfer

Question 2

Longitudinal waves

Answer 2

• waves in which the particles of the wave oscillate parallel to the direction of movement (propagation) meaning the wave particles are oscillating in the direction of energy transfer
• ex- sound waves, laying a slinky flat on a table top and tapping it on the end

Question 3

Wavelength definition

Answer 3

the distance from one maximum (crest) of the wave to the next

Question 4

Frequency

Answer 4

The number of wavelengths passing a fixed point per second

-measured in hertz (Hz) or cycles per second (cps)

Question 5

Speed (v) equation

Answer 5

v= frequency x wavelength

Question 6

Period (T) definition and equation

Answer 6

• inverse of frequency, the number of seconds per cycle

- T= 1/frequency

Question 7

Displacement (x) in a wave describes

Answer 7

how far a particular point on the wave is from the equilibrium position

Question 8

Amplitude (A)

Answer 8

the maximum magnitude of displacement in a wave- NOT total displacement, which would be double the amplitude

Question 9

Timbre

Answer 9

The quality of sound

-determined by the natural frequency or frequencies of the object

Question 10

Forced Oscillation

Answer 10

if a periodically varying force is applied to a system, the system will then be driven at a frequency equal to the frequency of the force

Question 11

Damping

Answer 11

A decrease in amplitude of a wave caused by an applied or nonconservative force

Question 12

Frequency of sound

Answer 12

Pitch- lower frequency=lower pitch

Question 13

Infrasonic waves

Answer 13

sound waves with frequencies below 20 Hz

Question 14

Ultrasonic waves

Answer 14

sound waves with frequencies above 20,000 Hz

Question 15

Doppler Effect

Answer 15

Describes the difference between the actual frequency of a sound and its perceived frequency when the source of the sound and the sounds detector are moving relative to one another
-moving toward each other- perceived frequency(f1) is greater than the actual frequency (f)

Question 16

Shock wave

Answer 16

when an object that is producing sound while traveling at or above the speed of sound allows wave fronts to build upon one another at the front of the object (creating a larger amplitude at that point). The highly condensed wave front is a shock wave
-can cause physical disturbances as it passes through other objects

Question 17

Sonic boom

Answer 17

-the passing of a shock wave that creates a very high pressure followed by a very low pressure

Question 18

Intensity

Answer 18

the average rate of energy transfer per area across a surface that is perpendicular to the wave

• (power transported per unit area)
• units of W/m^2 (watts per square meter

Question 19

Intensity equation

Answer 19

I=P/A where P is the power and A is the area

Question 20

Amplitude and intensity relationship

Answer 20

intensity is proportional to the square of amplitude

-doubling the amplitude produces a sound wave that has four times the intensity

Question 21

Intensity and distance relationship

Answer 21

-intensity is inversely proportional to the square of the distance from the source

Question 22

Attenuation

Answer 22

• Damping
• The presence of a nonconservative force causes the system to decrease in amplitude during each oscillation
• does not have an effect on the frequency of the wave, so the pitch will not change
• explains why it is more difficult to hear in a confined or cluttered space: friction from the surfaces of the objects in the room decreases the sound waves amplitude

Question 23

Standing waves form whenever

Answer 23

whenever two waves of the same frequency traveling in opposite directions interfere with one another as they travel through the same medium

Question 24

Ultrasound

Answer 24

-uses high frequency sound waves outside the range of human hearing got compare the relative densities of tissues in the body

Question 25

Doppler ultrasound

Answer 25

-Used to determine the flow of blood within the body by detecting the frequency shift that is associated with movement toward or away from the receiver