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3 years ago

6

Ultrasound with a frequency of 4.40 MHz can be used to produce images of the human body. If the speed of sound in the body is th

e same as in salt water, 1.30 km/s, what is the length of a 4.40-MHz pressure wave in the body

1 answer:

viktelen [127]3 years ago

7 0

Answer:

0.295 m

Explanation:

Velocity of the wave= 1.3Kms-1= 1300ms-1

Frequency of the wave= 4.4MHz= 4400Hz

From

Velocity= wavelength × frequency

Wavelength= velocity/frequency

= 1300/4400

=0.295 m

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A 68.2 kg base runner begins his slide into second base while moving at a speed of 4.33 m/s. He slides so that his speed is zero

qwelly [4]

Answer:

$147.653J = W_f$

Explanation:

We know that:

$E_i - E_f = W_f$

where $E_i$ is the initial energy, $E_f$ is the final energy and $W_f$ is the energy lost due to friction.

so:

$\frac{1}{2}MV^2-0 = W_f$

Where M is the mass and V is the velocity of the runner, so:

$\frac{1}{2}(68.2kg)(4.33m/s)^2 = W_f$

$147.653J = W_f$

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4 years ago

Object A has a mass of 8.0 kg and is accelerating at 4.0 m/s2. Object B has a mass of 10.0 kg and is accelerating at 3.0 m/s2. O

Leviafan [203]

Answer:

b. B, A, C

Explanation:

To solve this problem, let us find the net forces they are experiencing.

Net force = mass x acceleration

Object A; mass = 8kg and acceleration = 4m/s²

Net force = 8 x 4 = 32N

Object B; mass = 10kg and acceleration = 3m/s²

Net force = 10 x 3 = 30N

Object C: mass = 7kg and acceleration = 5m/s²

Net force = 7 x 5 = 35N

So, increasing order of their net force;

B < A < C

6 0

3 years ago

A golf ball starts with a speed of 2 m/s and slows at a constant rate of 0.5 m/s2, what is its velocity after 2 s?

jeka57 [31]

Answer:

3m/s

Explanation:

Given parameters:

Initial speed = 2m/s

Acceleration = 0.5m/s²

Time = 2s

Unknown:

Final speed = ?

Solution:

To solve this problem, we apply the right motion equation;

V = U + at

V is the final speed

U is the initial speed

a is the acceleration

t is the time

V = 2 + (2 x 0.5)

V = 2 + 1

V = 3m/s

8 0

3 years ago

The joule and the kilowatt-hour are both units of energy. 15 kw · h is equivalent to how many joules? answer in units of j.

choli [55]

The solution for the problem is:

1 Watt = 1 Joule per second
1 Watt*second = 1 Joule

a Kilowatt is 1,000 Watts
an hour is 60 seconds times 60 minutes or 3,600 seconds
a Kilowatt * hour is 1,000 Watts in 3,600 seconds

15 W*h = 15,000 Watt*hour = 15,000 Watt * 3,600 seconds = 54,000,000 Watt*second

54,000,000 Watt*second = ? Joules
54,000,000 Joules / second = 54,000,000 Watts

3 0

3 years ago

For the circuit shown, R = 75.0 ohms, L= 55.0 mg, and C = 25.0 μC. The power source has 12.0 V arms and a frequency of 60.0 Hz.

Natasha_Volkova [10]

Explanation:

Given that,

Resistance R = 75.0 ohms

Inductance L = 55.0 mH

Capacitance $C = 25.0\ \mu C$

Voltage V = 12.0 V

Frequency f = 60.0 Hz

We need to calculate the angular frequency

Using formula of angular frequency

$\omega = 2\pi f$

Put the value into the formula

$\omega =2\times3.14\times60.0$

$\omega=376.8\ rad/s$

(a). We need to calculate the value of $X_{L}$

Using formula of $X_{L}$

$X_{L}=\omega\times L$

Put the value into the formula

$X_{L}=376.8\times55.0\times10^{-3}$

$X_{L}=20.724\ \Omega$

(b). We need to calculate the value of $X_{L}$

Using formula of $X_{C}$

$X_{C}=\dfrac{1}{\omega C}$

$X_{C}=\dfrac{1}{376.8\times25.0\times10^{-6}}$

$X_{C}=106.16\ \Omega$

(c). We need to calculate the value of Z

Using formula of impedance

$Z=\sqrt{R^2+(X_{L}-X_{C})^2}$

Put the value into the formula

$Z=\sqrt{75.0^2+(20.724-106.16)^2}$

$Z=113.68\ \Omega$

(d). We need to calculate the rms current

Firstly we need to calculate the current

Using formula of current

$I=\dfrac{V}{R}$

Put the value into the formula

$I=\dfrac{12.0}{75.0}$

$I=0.16\ A$

Using formula of rms current

$I_{rms}=\dfrac{I_{0}}{\sqrt{2}}$

$I_{rms}=\dfrac{0.16}{\sqrt{2}}$

$I_{rms}=0.113\ A$

(e). We need to calculate the rms voltage across the resistor

Using formula of rms voltage

$V_{rms}=I_{rms}\times R$

$V_{rms}=0.113\times75.0$

$V_{rms}=8.475\ V$

(f). We need to calculate the rms voltage across the inductor

Using formula of rms voltage

$V_{rms}=I_{rms}\times X_{L}$

$V_{rms}=0.113\times20.724$

$V_{rms}=2.342\ V$

(g). We need to calculate the rms voltage across the capacitor

Using formula of rms voltage

$V_{rms}=I_{rms}\times X_{C}$

$V_{rms}=0.113\times106.16$

$V_{rms}=11.99\ V$

(h). We need to calculate the dissipated power by the circuit

Using formula of dissipated power

$P=RI^2$

Put the value into the formula

$P=75.0\times0.113^2$

$P=0.958\ W$

Hence, This is the required solution.

3 0

3 years ago