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never [62]
3 years ago
9

A sound source of frequency f moves with constant velocity (less than the speed of sound) through a medium that is at rest. A st

ationary observer hears a sound whose frequency is appreciably different from f because:________
a. interference effects set up a standing-wave pattern that alters the frequency
b. the wavelength established in the medium is not the same as it would be if the source were at rest.
c. the equation that relates velocity of propagation, frequency, and wavelength of a sound traveling through a medium does not apply in this situation
d. the sound wave travels through the medium with a velocity different from that which it would have if the source were at rest
Physics
1 answer:
ANTONII [103]3 years ago
7 0

Answer:

The correct answer is d

Explanation:

In this exercise they ask us which statement is correct, for this we plan the solution of the problem, this is a Doppler effect problem, it is the frequency change due to the relative speed between the emitter and the receiver of sound.

The expression for the Doppler effect of a moving source is  

f ’= (v / (v- + v_s) f  

From this expression we see that if the speed the sound source is different from zero feels a change in the  frequency.

The correct answer is d

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3. Consider a locomotive and the rest of a freight train to be a single object. Suppose the locomotive is pulling the train up a
34kurt

Answer:

The friction force and the x component for the weight should be the reaction forces that are opposite and equal to the action force, which causes the locomotive to move up the hill if the velocity of the locomotive remains constant.  

Explanation:

<u>When the locomotive starts to pull the train up, appears two reaction forces opposed to the action force in the direction of the move. </u>

The first one is due to the friction between the wheels and the ground, it will be the friction force (Fr):

Fr = μ*Pₓ =μmg*sin(φ)        

<em>where μ: friction dynamic coefficient, Pₓ: is the weight component in the x-axis, m: total mass = train's mass + locomotive's mass, g: gravity, and sin(φ): is the angle respect to the x-axis.</em>              

And the second one is the x component for the weight (Wₓ):

Wₓ = mg*cos(φ)  

<em>where cos(φ): is the angle respect to the y-axis.    </em>

<em> </em>

These two forces should be the same as the action force, which causes the locomotive to move up the hill if the velocity of the locomotive remains constant.          

3 0
4 years ago
What mass of silver will occupy a volume of 87.75 mL?<br>The density of silver is 10.49 g/mL.​
Anastaziya [24]

Answer:

The mass of silver that will occupy a volume of 87.75 mL is 920.5 grams.

Explanation:

Density is defined as the property that matter, whether solid, liquid or gas, has to compress into a given space. In other words, density is a quantity that allows us to measure the amount of mass in a certain volume of a substance. Then, the expression for the calculation of density is the quotient between the mass of a body and the volume it occupies:

density=\frac{mass}{volume}

So the density of silver is 10.49 g / mL indicates that 10.49 g occupies a volume of 1 mL. Then a rule of three can be applied in the following way: if in 1 mL a mass of 10.49 g is occupied, in 87.75 mL how much mass will it occupy?

mass=\frac{87.75 mL*10.49 g}{1 mL}

mass= 920.5 g

<u><em> The mass of silver that will occupy a volume of 87.75 mL is 920.5 grams.</em></u>

5 0
3 years ago
Calculate the percentage increase in length of a wire of diameter 2.2 mm stretched by a load of
vesna_86 [32]

Answer:

0.21%

Explanation:

We are given;

Mass; m = 100 kg

Diameter; d = 2.2 mm = 2.2 × 10^(-3) m

Young's modulus; E = 12.5 x 10^(10) N/m².

Formula for area is;

A = πd²/4

A = (π/4) x (2.2 x 10^(-3))²

A = 3.8 x 10^(-6) m²

Force; F = mg

g is acceleration due to gravity and has a constant value of 9.8 m/s²

F = 100 × 9.8

F = 980 N

Formula for young's modulus is;

E = Stress/strain

Formula for stress = F/A

Formula for strain = ΔL/L

Thus;

E = (F/A)/(ΔL/L)

Making ΔL/L the subject, we have;

ΔL/L = (F/A)/E

Plugging in the relevant values;

ΔL/L = 980/(3.8 x 10^(-6) × 12.5 × 10^(10))

ΔL/L = 0.0021

Then percentage increase in length of a wire = 0.0021 × 100% = 0.21%

8 0
3 years ago
Electromagnetic waves are produced when _____.
Tju [1.3M]

Answer: The correct answer is a.

Explanation:

Electromagnetic wave is a wave in which the magnetic field and the electric field are perpendicular to each other.

Both fields are directed in the direction of the propagation of the electromagnetic wave. It travels with the speed of the light.

The motion of the electric field produces both electric field and the magnetic field.

The electromagnetic waves are produced when an electric charge vibrates or accelerates.

Therefore, the correct option is (a).

6 0
3 years ago
Read 2 more answers
The eye of a hurricane passes over grand bahama island in a direction 60.0° north of west with a speed of 41.0 km/h. three hour
Ksivusya [100]

initial velocity is given as 41 km/h at 60 degree North of West

v_i = -41 cos60\hat i + 41 sin60 \hat j

v_i = -20.5 \hat i + 35.5 \hat j

After some time the velocity is given as

v_f = 25 \hat j

now we can find the acceleration

a = \frac{v_f - v_i}{t}

a = \frac{25\hat j - (-20.5 \hat i + 35.5 \hat j)}{3}

a = 6.83 \hat i - 3.5 \hat j

now the distance is given by

d = v*t + \frac{1}{2} at^2

d = (-20.5 \hat i + 35.5 \hat j)*4.5 + 0.5*(6.83 \hat i - 1.5 \hat j)* 4.5^2

d = -92.25\hat i + 159.75\hat j + 69.15\hat i - 15.19\hat j

d = -23.1 \hat i + 144.56\hat j

so the magnitude of distance is

d = \sqrt{23.1^2 + 144.56^2} = 146.4 km

8 0
3 years ago
Read 2 more answers
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