Phys Chapter 20 Q&A and Fill-ins

Most sounds are produced by a _____ matter

vibrating

Sonography is sound due to a _____ material

piezoelectric

Vibrating material sends a disturbance in the form of what type of sound waves?

longitudinal

Under ordinary conditions, frequency of source = frequency of _____ _____

sound waves

Frequency is also called what?

pitch

We _____ hear infrasonic and ultrasonic sound

cannot

Some infrasonic waves are felt like what example?

earthquake

Sound waves are created by a series of what 2 things?

compression & rarefactions

Sound waves must travel through a _____ and cannot travel through a _____

medium; vacuum

Sound waves are what type and shape?

mechanical; longitudinal

Any _____ substance can transmit sound

elastic

Sound travels about __ times faster in water than in air and about __ times faster in steel than in air

4; 15

How fast does sound travel in air?

343 m/s

How fast does sound travel in water?

1500 m/s

How fast does sound travel in the human body (soft tissue & blood)?

1540 m/s

What 3 things does the speed of sound depend on?

wind, temperature & humidity

Does warm or cold air travel sound faster?

warm

_____ speed cannot be changed by a sonographer

propagation

What 2 things determine propagation speed?

density & stiffness

How fast does sound travel in the lungs?

300-1200 m/s

How fast does sound travel in fat?

1450 m/s

How fast does sound travel in tendons?

1840 m/s

How fast does sound travel in bones?

2000-4000 m/s

When reflection happens to sound traveling through air it is often called what?

echo

Multiple reflections are called what?

reverberations

What 3 things cause wave refraction?

Temperature changes, humidity, & wind changes

The path of a wave bends towards or into regions where it travels _____

slower

The path of a wave bends away from regions where it travels _____

faster

Multiple reflections and refractions are _____ waves

ultrasound

Sound boards transmit vibrations into a _____

cavity

Natural frequency depends on what 2 things?

elasticity & shape of object

Power is proportional to____ _____

amplitude squared