In addition to producing images, ultrasound can be used to heat tissues of the body for therapeutic purposes. An emitter is placed against the surface of the skin; the amplitude of the ultrasound wave at this point is quite large. When a sound wave hits the boundary between soft tissue and bone, most of the energy is reflected. The boundary acts like the closed end of a tube which can lead to standing waves. Suppose 0.7 MHz ultrasound is directed through a layer of tissue at a bone 0.55 cm below the surface. Remember, sound waves in the body travel at 1540 m/s. Explain.

Answers

Answer 1

Answer:

ΔT = 4.058 10²⁰ [tex]\frac{S_o^2}{r^2 \ c_e}[/tex]

Explanation:

In this experiment the system can be approximated as a tube with one end open and the other closed.

The open end is where the ultrasound emitter is and the closed end where the limit between the tissue and the bone is, the length of the tube is L = 0.55 cm = 5.5 10⁻³ m

a node is formed at the closed end and a belly at the open end, so the resonance has the form

             λ = 4L                    1st harmonic

             λ = 4/3 L                third harmonic

             λ = 4/5 L                fifth harmonic

             λ = 4L / (2n + 1)     n = 0, 1, 2, (2n + 1)

This wave is a standing wave therefore energy density remains in place

                P = 1/2 ρ v (w S₀)²

                 

angular velocity is related to frequency

               w = 2π f

we substitute

                E = P = 2π² ρ v f² S₀²

if this energy per unit area is transformed into heat

                E = m c_e DT

let's use the concept of density

                ρ = m / V

                m = ρ V

if there are no losses in the system

       ½ π² ρ v f² S₀² = ρ V c_e ΔT

       ΔT = [tex]\frac{\pi ^2 \ v \f^2 S_o^2}{2V \ c_e}[/tex]

When analyzing this expression the temperature increase is

* quadratic at the frequency and maximum amplitude of the wave

* proportional to the speed of the wave in the tissue

* inversely proportional to tissue volume

       

we can approximate the volume of the tissue to the volume of a cylinder tube

            V = π r² L

             

           ΔT = [tex]\frac{\pi \ v \ f^2 S_o^2 }{r^2 \ L \ c_e}[/tex]

           

we calculate

            ΔT = π 1450 (0.7 10⁶)² S₀² /( r² 5.5 10-3 c_e)

            ΔT = 4.058 10²⁰ [tex]\frac{S_o^2}{r^2 \ c_e}[/tex]


Related Questions

What are the parts of a torch light name them​

Answers

Answer: Batteries,the case of the torch,reflector,contacts,switch and lens and the light/bulb Hope i helped :)

Which organisms were first responsible for depleting carbon dioxide from the atmosphere, replacing it with oxygen?

A) Plants

B) Dinosaurs

C) Cyanobacteria

D) Trilobites

Answers

C) Cyanobacteria is the answer
A) Plants

Hopes this helps

3
Explain the working principles
of 아
has/ Constant volume
thermometer
a gas​

Answers

Answer:

A constant volume gas thermometer works on a thermometric property of " change in pressure with temperature at a constant volume"

If a magnet can cut into a small piece , each piece will remain a magnet ? Explain this phenomenon

Answers

yes ,each piece will remain a magnet because the small pieces will cut into north and south

when a light beam emerges from water into air, the average light speed ____.

a. increases
b. decreases
c. remains the same
d. not provided

Answers

Answer:

Increases

Explanation:

The light is emerging from a denser medium to rarer medium so the average light speed increases.

When a light beam emerges from water into air, the average light speed increases.

What is refraction?

      The bending of a ray passes at an angle from one medium to another in which the speed will be different, as when light passes from air into water and also from water into air can be known as refraction.

      When light travels from water to air, the angle from water to air the light  gets speeds up and then its changes direction. The light turns away from the normal line. Because the light moves from a denser medium to the rarer medium. But from air to water the speed will be decreased because in that case the light travels from the rarer medium to the denser medium.

Hence, the light beam when passes, the average speed gets increased.

So, Option A is the correct answer.

Learn more about refraction,

https://brainly.com/question/2660868

#SPJ2

Which statement did John Dalton make about atoms?
A. there are distinct kinds of atoms
B. the atom is made up of smaller particles
C. the atom has a small, dense center
D. the energy of an electron depends on its specific orbit

Answers

Answer:

B

Explanation:

Atoms are made by electrons, neutrons and protons

Answer:

A. there are distinct kinds of atoms

Explanation:

According to Dalton's atomic theory, the atom is indivisible. Thus, we know that B is incorrect. Additionally, C can't be correct because when Dalton was alive, the nucleus (the small, dense center) hadn't yet been discovered. Finally, D can't be correct either since Bohr's discoveries about electron orbits hadn't yet been made. Knowing that, it must be A!

Also, I just did the quiz, and it was A. Dalton believed that there are distinct kinds of atoms!

Polarizing windows, filters, etc. are often used to reduce the amount of light that enters the lens of a camera or into a room or a car. A library atrium has an overhead skylight that lets in too much light during the day which heats up the interior of the library far too much. The building engineer installs new double paned polarizing sky lights to reduce the intensity. If sunlight, which is unpolarized, has an average intensity of 1366 W/m2 what angle should the polarizing axis of the second pane of the window make with the polarizing axis of the first pane of the window in order to reduce the intensity of the sunlight to 33% of the original value

Answers

Answer:

 θ = 35.7º

Explanation:

For this exercise we must use the law of Malus

          I = I₀ cos² θ

where the angle is between the two polarizers.

When the unpolarized light from the sun reaches the first polarizer, only the light polarized in the direction manages to be transmitted, which is why

          I₁ = I₀ /2

this light reaches the second polarizer

           I₂ = I₁ cos² θ

           I₂ = I₀/2    cos² θ

           cos² θ = 2 I₂ / Io

indicate that the transmitted light is 33% = 0.33 I₀

          cos² θ = 2 0.33

          cos θ = √0.66

          θ = cos⁻¹ 0.8124

          θ = 35.7º

what heat transfer occurs when warm air rises

Answers

Convection. When a fluid such as air or water touches a hot object, it can heat up and then move in bulk as a fluid, thereby carrying the heat quickly to new locations. Hot air rising is a common example of heat convection.

what is the best structure for a egg dropping project you will be name brainiest

Answers

Answer:

bubble wrap in stuff animal

Explanation:

did it

Answer:

i would say putting like pillows around it i had to do it once and i won like that so

Explanation:

A uniform rod of length 50cm and mass 0.2kg is placed on a fulcrum at a distance of 40cm from the left end of the rod. At what distance from the left end of the rod should a 0.6kg mass be hung to balance the rod?
a.48 cm
b. 50 cm
c. 45 cm
d. the rod can not be balanced with this mass. e.42 cm
NO LINKS. ​

Answers

I’m pretty sure it’s b

Which of the following is an example
of a measure of the
mass of an object?
A. 65 centimeters
B. 65 grams
C. 65 light-years
D. 65 feet

Answers

Answer:

Grams

Explanation:

Because that is the definition

Answer:

65 grams

Explanation:

A 12 ohm resistor and a 24 ohm resistor are connected in parallel across a 6.0 V battery. The correct statement from the following is a. the current is the same in each resistor. b. the power dissipated is the same in each resistor. c. the larger current is in the larger resistor. d. the voltage difference between the ends of each resistor is the same.

Answers

Answer:

d. the voltage difference between the ends of each resistor is the same.

Explanation:

A resistor is a circuit component that offers opposition to the flow of current. Resistors may be connected in series or in parallel.

Resistors in parallel are connected at common junctions. The potential difference (voltage difference between the ends of each resistor) is the same for each resistor in a parallel connection while the current across each resistor is different.


_PCi5 + _H20 + _H3PO4 _HCI
A.) 1,3,1,5
B.) 2,4,1,5
C.) 1,4,1,5
D.) 2,1,2,5


Answers

Answer:

C

Explanation:

because of the kids are doing well and staying in the middle of the day early to get a new phone number for home now deep

A ____________ galaxy has arms of gas and dust; where as _____________ galaxy is a category of galaxy that does not have a distinctive shape.

Question 1 options:

elliptical, an elliptical


irregular, a barred-spiral


bar, a spiral


spiral, an irregular

Answers

Answer:

spiral, an irregular

Explanation:

i took the test :)

if a car travels 200 m to the east in 8.0s what is the car's average velocity.

Answers

Answer:

25mph

Explanation:

you do distance divided by time. 200/8=25

HELP PLEASEEEEEEEEEEEE

Answers

the answer would be a

The botanist from the nursery is planning to develop a large number of new spider plants with larger flowers. Identify the type of reproduction the botanist should use to develop the new spider plants and explain why this type of reproduction is preferable.

Answers

Answer:

Sexual reproduction.

Explanation:

Reproduction can be defined as a biological process which typically involves living organisms producing an offspring.

Basically, there are two (2) methods of reproduction and these are;

I. Asexual reproduction: it involves the cloning of a living organism to produce an offspring because there is only a single parent.

II. Sexual reproduction: it involves the combination of the genome (gamete) of a male and female living organism during fertilization.

In this scenario, the botanist from the nursery plans to develop a large number of new spider plants that has larger flowers. Thus, the type of reproduction the botanist should use to develop the new spider plants is sexual reproduction because it would help the parent plant reproduce offsprings with different traits such as spider plants with large flowers. Also, the botanist should use sexual reproduction rather than asexual reproduction because asexual reproduction will only make the parent plant reproduce that have the same type of traits as themselves.

plz help.me guys

6xy – 12x y + 15x3y? – 3x?y? by 3x²y​

Answers

Answer:

2xy-12xy+15x3y?-3x?y?by3l 3x2y

Bent over row trains what specific muscle?
O A. triceps
O B. trapezius
O C. latissimus dorsi
D. pectoralis major

Answers

I believe it is A for the answer

a car traveling in a highway brakes to a stop without skidding. what happens to its kinetic energy? can that energy be recovered and reused?

Answers

Answer:

A car traveling on a highway takes to stop without skidding. What happens to its kinetic energy? ... The energy goes to parts of the brakes. No, the energy can only be reused if there is a heat pump present

Complete the sentence below using the words provided in parentheses (). For two universes that are the same size, the universe with the faster expansion rate must be _______ (younger/older) than the universe with the slower expansion rate. The slope of the line in the Hubble plot of the ______ (younger/older) universe will be ______ (steeper/flatter)

Answers

Answer:

For two universe that is the same size, the universe with the faster expansion rate must be younger than the universe with a slower expansion rate. The slope in the line of the Hubble plot of the older universe will be flatter.

Explanation:

Hubble's law establishes a direct relationship between a galaxy's distance and its redshift-determined recessional velocity. The redshifts of galaxy clusters and distant galaxies are equivalent and proportional to their distances from us, according to Hubble's theorem.

Thus, to copy and complete the given question.

For two universe that is the same size, the universe with the faster expansion rate must be younger than the universe with a slower expansion rate. The slope in the line of the Hubble plot of the older universe will be flatter.

what's the temperature 32°F in degrees Celsius

Answers

Answer:

0 degrees Celsius

Explanation:

0 Celsius . That’s the answer you’re Welcome :)

You have 3 resistors and a battery to form a closed circuit. Two 2-Ohm resistors are in series with each other. The combination of those two resistors is in parallel with a 4-Ohm resistor. The total voltage of this circuit is 12 Volts. The total current and resistance of this circuit is a. 2 Ohms, 6 Amps b. 8 Ohms, 1.5 Amps c. 6 Ohms, 2 Amps d. 1.5 Ohms, 8 Amps

Answers

Answer:

Option 2

Explanation:

Given

Two 2-Ohm resistors are in series  and these two resistors are in parallel with a 4-Ohm resistor

Equivalent resistance of two resistors in series = R1 + R2 = 2+2 = 4 Ohm

Equivalent resistance of two 4 Ohm resistors is parallel =1/ (1/4 +1/4) = 2 Ohm

Voltage = 12 Volts.

Hence, current = V/R = 12/2 = 6 Amp

Option 2 is correct

Please help

Which of the following is an example of heat energy being transformed into mechanical energy

A. An electric mixer being used to beat eggs

B. A person turning a crank to sharpen a pencil.

C. A car battery being used to power a car radio

D. Boiling water producing steam used to power a boat​

Answers

Answer:

D

Explanation:

because it is the only one that has something to do with heat keyword would be boiling

A self-driving car traveling along a straight section of road starts from rest, accelerating at 2.00 m/s2 until it reaches a speed of 25.0 m/s. Then the vehicle travels for 39.0 s at constant speed until the brakes are applied, stopping the vehicle in a uniform manner in an additional 5.00 s.
(a) How long is the self-driving car in motion (in s)?
(b) What is the average velocity of the self-driving car for the motion described? (Enter the magnitude in m/s.) m/s

Answers

Answer:

[tex]56.5\ \text{s}[/tex]

[tex]21.13\ \text{m/s}[/tex]

Explanation:

v = Final velocity

u = Initial velocity

a = Acceleration

t = Time

s = Displacement

Here the kinematic equations of motion are used

[tex]v=u+at\\\Rightarrow t=\dfrac{v-u}{a}\\\Rightarrow t=\dfrac{25-0}{2}\\\Rightarrow t=12.5\ \text{s}[/tex]

Time the car is at constant velocity is 39 s

Time the car is decelerating is 5 s

Total time the car is in motion is [tex]12.5+39+5=56.5\ \text{s}[/tex]

Distance traveled

[tex]v^2-u^2=2as\\\Rightarrow s=\dfrac{v^2-u^2}{2a}\\\Rightarrow s=\dfrac{25^2-0}{2\times 2}\\\Rightarrow s=156.25\ \text{m}[/tex]

[tex]s=vt\\\Rightarrow s=25\times 39\\\Rightarrow s=975\ \text{m}[/tex]

[tex]v=u+at\\\Rightarrow a=\dfrac{v-u}{t}\\\Rightarrow a=\dfrac{0-25}{5}\\\Rightarrow a=-5\ \text{m/s}^2[/tex]

[tex]s=\dfrac{v^2-u^2}{2a}\\\Rightarrow s=\dfrac{0-25^2}{2\times -5}\\\Rightarrow s=62.5\ \text{m}[/tex]

The total displacement of the car is [tex]156.25+975+62.5=1193.75\ \text{m}[/tex]

Average velocity is given by

[tex]\dfrac{\text{Total displacement}}{\text{Total time}}=\dfrac{1193.75}{56.5}=21.13\ \text{m/s}[/tex]

The average velocity of the car is [tex]21.13\ \text{m/s}[/tex].

What is this answer? A blank is a combination of two or more substances, elements, compounds, or both, in the same place but not chemically combined

Answers

A mixture? lmk if that’s the right answer! your welcome :)

If the period of a given wave is 6 seconds, what is the frequency of the wave?
A. 17 Hz
B. 0.17 Hz
C. 0.017 Hz
D. 1.7 Hz

Answers

Answer:

[tex]\text{B. }0.17\:\mathrm{Hz}[/tex]

Explanation:

The frequency of a wave is given by [tex]f=\frac{1}{t}[/tex], where [tex]t[/tex] is the period of the wave.

Substituting [tex]t=6[/tex], we get:

[tex]f=\frac{1}{6}\approx \boxed{\text{B. }0.17\:\mathrm{Hz}}[/tex]

At this point, you have learned that heat is the ________ of ________ energythat is possessed by an object due to the motion of its particles. When this happens, an object’s ____________ changesfrom cool to warmer.There are ways of heat transfer: (a) ____________, where heat is transferred between materials that are in direct contact with each other. While (b) ____________, occurs when heat is transferred by electromagnetic waves (through space). And lastly, (c) ____________is transfer of heat in fluids which makesthe hot fluids to rise and cold fluidstosink

Answers

Abbreviate the sentences

During a football game player A (mass 120kg velocity 5.5m/s [L]) tackles and grabs player B (mass 105kg velocity 7.9m/s [R]). What is the final speed of the two players immediately after the collision?

Answers

Answer:

6.62m/s

Explanation:

Given data

M1= 120kg

U1= 5.5m/s

M2= 105kg

U2= 7.9m/s

The system experiences an inelastic collision, the expression for inelastic collision is

M1U1+ M2U1= (M1+M2)V

Subsitute

120*5.5+ 105*7.9= (120+105)*V

660+ 829.5= (225)*V

1489.5= (225)*V

Divide both sides by 225

V= 1489.5/225

V= 6.62m/s

Hence the common velocity is 6.62m/s

What is the length of a string with a mass of 2.5 kg, with a
tension of 20 N, if the speed of wave on the string is 2 m/s?
a 0.8 m
b 0.4 m
C 0.5 m
d 1.0 m
e 0.1 m

Answers

B 0.4 m should be correct if not it is A
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