PHYSICS CH 1-4

unrelated

two items that are not associated

directly related or directly proportional

two items that are associated such that when one item increases, the other increases

related or proportional

two items that are associated or affiliated

Inversely related or inversely proportional

Two items are associated such that when one item increases, the other decreases.

Reciprocal Relationship

When two numbers with a reciprocal relationship are multiplied together, the result is one.

Which prefix/symbol/meaning for 10^9?

giga/G/billion

Which prefix/symbol/meaning for 10^6?

mega/M/million

Which prefix/symbol/meaning for 10^3?

kilo/k/thousand

Which prefix/symbol/meaning for 10^2?

hecto/h/hundred

Which prefix/symbol/meaning for 10^1?

deca/da/ten

Which prefix/symbol/meaning for 10^-1?

deci/d/tenth

Which prefix/symbol/meaning for 10^-2?

centi/c/hundreth

Which prefix/symbol/meaning for 10^-3?

milli/m/thousandth

Which prefix/symbol/meaning for 10^-6?

micro/μ/millionth

Which prefix/symbol/meaning for 10^-9?

nano/n/billionth

Match the following pair with the prefixes:

billions & billionths

giga(G) & nano(n)

Match the following pair with the prefixes:

millions & millionths

mega(M) & micro(μ)

Match the following pair with the prefixes:

thousands & thousandths

kilo(k) & milli(m)

Match the following pair with the prefixes:

hundreds & hundredths

hecto(h) & centi(c)

Match the following pair with the prefixes:

tens & tenths

deca(da) & deci(d)

Sound is a ____________, ____________ wave that travels in a straight line.

mechanical and longitudinal

Sound needs a __________________________in which to travel.

medium

Molecules are alternately ____________________ (squeezed together) and ___________________ (stretched apart).

compressed and rarefied

Mechanical is the same as

practical motion

Name the three acoustic variables:

pressure, density, distance

Pressure

concentration of force in an area

Name the unit for the following acoustic variable: pressure

pascals (Pa)

Density

concentration of mass in volume or relative weight of a material

Name the unit for the following acoustic variable: density

kg/cm^3

Distance

measure of particle in motion

Name the unit for the following acoustic variable: distance

cm, feet, mile, mm

How many acoustic parameters are there?

7

Name the Acoustic Parameters:

period, frequency, amplitude, power, intensity, wavelength, propagation speed

What are the acoustic parameters used for?

describe the characteristics of a sound wave

transverse wave

particles move in a direction that is perpendicular to the direction that the wave propagates

longitudinal wave

particles move in the same direction that the wave propagates

Which way transverse waves move?

up and down

Which way longitudinal waves move?

side by side

Soundwave = ________________

longitudinal wave

In-Phase Waves

when peaks occur at the same time & place; "in step"

Out-of-Phase Waves

peaks & troughs occur at different times; "out of step"

What is interference?

the combination of two or more waves that results in a single wave

With what kind of wave does constructive interference happen?

in-phase waves

With what kind of wave does destructive interference happen?

out-of-phase waves

Interference of Waves with Different Frequencies

When the frequencies of the waves differ, both constructive and destructive interference occur.

Parameters

describes features of a sound wave (characteristic or factor, aspect, element)

Period

is the time it takes a wave to vibrate a single cycle

Unit

period is reported in units of time

Period is determined by the ____________ source only, not by the _____________.

sound, medium

Can a sonographer change the period?

No

Parameter is determined by:

sound source or medium

Period is a unit of ___________.

time

Frequency is _________________, also known as "_________".

cycles per second or Hertz

"Ultra" sound is reported in ______hertz or ____________ cycles per second.

megahertz or millions

Frequency

the number of particular events that occur in a specific duration of time

Can a sonographer change the frequency?

No

1 cycle/second = ___________

1 Hertz (Hz)

Typical values for frequency:

2MHz (2 million per second) to 15 MHz (15 million per second)

infrasound

less than 20 Hz

audible

between 20 Hz and 20 kHz

ultrasound

greater than 20kHz

Period and frequency are also:

reciprocal

Period x Frequency = ?

1

3Hz = ?

1/3 s

Amplitude

the "bigness" of a wave

What are the 3 Bigness Parameters?

1) Amplitude

2) Power

3) Intensity

What is the most common unit in amplitude?

decibels (dB)

Can a sonographer change the amplitude?

Yes

Amplitude is only determined by the _____ ______.

sound source

Power

the rate of energy transfer or rate at which work is performed

What can also describe the "bigness" of a wave, besides amplitude?

power and intensity

Power has units of ________.

Watts

Can a sonographer change the power?

Yes

What does this equation means?

power ∝ amplitude^2

power is proportional tp the wave's amplitude squared

Intensity

concentration of energy in a sound beam

Can a sonographer change the intensity?

Yes

Why is intensity the same as power in the following equation?

I ∝ P ∝ A^2

because they are directly related

Why is intensity the same as power in the following equation?

intensity (W/cm^2) = power (w)/area (cm^2)

if power is at the top, that indicates that power and intensity are directly related

Wavelength

the distance or length of one complete cycle

Wavelength is determined by both the ___________________ and the ________________.

source, medium

Can the sonographer change the wavelength?

No

Equation to find the wavelength of a sound wave in soft tissue:

wavelength (mm) = 1.54mm/µs /frequency (MHz)

propagation speed

the rate at which a sound wave travels through a medium

Speed is determined only by a _____________________.

medium

Can a sonographer change the speed?

No

What is the slowest tissue type?

Lung

What is the speed of lung?

500 m/s

What is the average tissue type?

human soft tissue

What is the speed of human soft tissue?

1,540 m/s, 1.54 km/s, or 1.54 mm/µs

What is the fastest tissue type?

bone

What is the speed of bone?

3,500 m/s

Stiffness and speed are _______________ related.

directly

Density and speed are _______________ related.

inversely

Stiffness

the ability of an object to resist compression

Stiffness / Speed

Thumbs Up/ Thumbs Up

Density / Speed

Thumbs Up / Thumbs Down

How are the following parameters related--- directly, inversely, or unrelated? frequency and period

inversely

How are the following parameters related--- directly, inversely, or unrelated? amplitude and power

directly

How are the following parameters related--- directly, inversely, or unrelated? amplitude and intensity

directly

How are the following parameters related--- directly, inversely, or unrelated? power and intensity

directly