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Yakvenalex [24]
3 years ago
11

Expectant mothers many times see their unborn child for the first time during an ultrasonic examination. In ultrasonic imaging,

the blood flow and heartbeat of the child can be measured using an echolocation technique similar to that used by bats. For the purposes of these questions, please use 1500 m/s as the speed of sound in tissue. I need help with part B and C
To clearly see an image, the wavelength used must be at most 1/4 of the size of the object that is to be imaged. What frequency is needed to image a fetus at 8 weeks of gestation that is 1.6 cm long?
A. 380 kHz
B. 3.8 kHz
C. 85 kHz
D. 3.8 MHz
Physics
1 answer:
katrin2010 [14]3 years ago
4 0

Answer:

<em>380 kHz</em>

<em></em>

Explanation:

The speed of sound is taken as 1500 m/s

The length of the fetus is 1.6 cm long

The condition is that the wavelength used must be at most 1/4 of the size of the object that is to be imaged.

For this 1.6 cm baby, the wavelength must not exceed

λ = \frac{1}{4} of 1.6 cm = \frac{1}{4} x 1.6 cm = 0.4 cm =

0.4 cm = 0.004 m   this is the wavelength of the required ultrasonic sound.

we know that

v = λf

where v is the speed of a wave

λ is the wavelength of the wave

f is the frequency of the wave

f = v/λ

substituting values, we have

f = 1500/0.004 = 375000 Hz

==> 375000/1000 = 375 kHz ≅ <em>380 kHz</em>

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a square loop whose sides are long is made with copper wire of radius , assuming resistivity of copper is . if a magnetic field
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A square loop whose sides are long is made of copper wire of radius , given the resistivity of copper is . if the magnetic field perpendicular to the loop changes at a constant rate of I = 14.029 mA.

The basic characteristic of a substance that measures how effectively it resists an electric current is called electrical resistance. A material with low resistance is a material that easily conducts electric current. A Greek letter is often used to indicate resistivity. Electrical resistance is a basic property of a material that measures how strongly it resists an electric current. The SI unit for electrical resistance is the ohmmeter.

We use magnetic field as a tool to describe how the magnetic field is distributed in the space around and inside something of a magnetic nature. A material with low resistance is a material that easily conducts electric current. A Greek letter is often used to indicate resistivity. An ohmmeter is a unit of electrical resistance in the SI system.

Learn more about magnetic field here;

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The complete question is :

A square loop whose sides are 6.0-cm long is made with copper wire of radius 1.0 mm. If a magnetic field perpendicular to the loop is changing at a rate of 5.0 mT/s, what is the current in the loop?

4 0
1 year ago
Cocaine, which is derived from the coca leaf, is grown mostly in Colombia and its neighboring countries while heroin, which is d
nevsk [136]

Answer:

Because of the location, humidity and temperatures.

Explanation:

Coca is grown in humid and very humid subtropical forests, called yungas and

they form the lower floor of the upper Jungle, in the Central Andes, mostly in Peru and Bolivia. The  yungas are in contact with the rainforests of the lowlands in Amazonia, where it has been  started to expand coca cultivation recently (Dourojeanni, 1988). The optimum altitude is 1000 a  2000 meters (where cocaine content is higher), with optimal annual average precipitation, is 2000 meters  mm, but it is grown between 700 and 2000 msnm and with an average annual rainfall of 1000 to 4200 mm.

msnm = meters above sea level

6 0
3 years ago
A student is given three wires that are made from different materials, but each wire has the same physical dimensions. For a giv
Ymorist [56]

Answer:

Use the ammeter to measure the current that flows through each wire, because a larger current that flows through the wire corresponds to a smaller resistivity

Explanation:

Since they are connected to a constant voltage power source, the potential difference does not change. The potential difference is proportional to the product of the current and the resistance and, the resistance opposes the flow of electric current. It is clear to see that a large current that flows through the current means there is a lesser resistance to the flow of current at constant potential difference across the circuit.

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3 years ago
A man has a mass of 66 kg on earth. What’s his weight in pounds?
Vlad1618 [11]

Answer:

646.8 N

Explanation:

3 0
3 years ago
A ball is thrown upward at a 45° angle. Inthe absence of air resistance, the ballfollows aA. tangential curve.B. sine curve.C. p
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As ball is projected up in air at an angle of 45 degree without any air resistance

Let the initial speed will be v

now we will have

In x direction

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in y direction

v_y = vsin45

now displacement in x direction

x = (vcos45)t + 0

displacement in y direction

y = (vsin45)t - \frac{1}{2}gt^2

now from above two equations we have

y = (vsin45)\frac{x}{vcos45} - \frac{1}{2}g(\frac{x}{vcos45})^2

y = xtan45 - \frac{1}{2v^2cos^245}gx^2

so above equation is a quadratic equation and hence it will be a parabolic curve

so correct answer will be

<em>C. parabolic curve.</em>

8 0
3 years ago
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