In which of the following situations is the Doppler Effect absent?



The source and the observer are moving towards each other.



The observer is moving toward the source.



The source is moving away from the observer.



The source and the observer are both moving with the same velocity.

Answers

Answer 1

Answer:

Correct option is

C

The listener is moving towards the source of sound

The Doppler effect (or the Doppler shift) is the change in frequency or wavelength of a wave (or another periodic event) for an observer moving relative to its source.

So if both listener and source of sound are stationary or are moving with the same velocity that is relative velocity is zero, there won't be any change in frequency.

Thus, in this case, the effect will arise when a listener is moving towards the source of the sound.


Related Questions

An Olympic skier glides down a hill, inclined at 25° to the horizontal, at 18 m/s.

How long did it take for her to ski 800 m to the bottom of the hill?

44.4 s

10.5 s

4.0 s

1.6 s

Answers

Divide total meters by meters per second:

800 m / 18 m/s = 44.4 seconds

Answer: 44.4

Which processes result in the release of carbon? Select three options.

Animals break down food molecules to obtain energy.
The remains of producers are broken down by decomposers.
The remains of consumers are broken down by soil decomposers.
Producers take in carbon dioxide.
Producers make sugars and starches.

Answers

Answer:

The remains of producers are broken down by decomposers.

The remains of consumers are broken down by soil decomposers.

Animals break down food molecules to obtain energy.

Explanation:

Answer:

It is A. B. and C.

Explanation:

Hope this helps

A rod of length 0.82 m, rotating with an angular speed, 4.2 rad/s, about axes that pass perpendicularly through one end, has a mass of 0.63 kg, which is distributed uniformly along its length. Find the kinetic energies of the rod.

Answers

Answer:

Explanation:

KE = ½Iω²

ΚΕ = ½(mL²/3)ω²

ΚΕ = ½(0.63(0.82²)/3)4.2²

ΚΕ = 1.24541928

KE = 1.2 J

A car C moving with a speed of 65 km/h on a straight road is ahead of motorcycle M moving with the speed of 80 km/h in the same direction. What is the velocity of M relative to A?

Answers

Answer:

The answer is 15. Step by step is you times 80 by 65 and then you divided by 2 and you call your teacher

determine the total current on the circuit bellow

Answers

Answer:

  170/179 A ≈ 949.7 mA

Explanation:

Finding equivalent impedance of a bridge network can be simplified by converting one end of it from a Δ to a Y configuration. The equivalent resistance in the Y connection is the product of the two resistors connected to that node, divided by the sum of all three resistors.

Considering the left side of the top two branches, the equivalent Y network values are ...

  (10)(15)/(10+15+25) = 150/50 = 3 . . . ohms

connected to the right-end node

  (25)(10)/50 = 5 . . . ohms

connected to the top-center node, and ...

  (25)(15)/50 = 7.5 . . . ohms

connected to the center node of the middle branch.

__

Then the top two branches of this circuit have an equivalent impedance equal to 3 ohms in series with the parallel combination of (5+20) ohms and (7.5+10) ohms. That value is ...

  3 + (25)(17.5)/(25 +17.5) = 226/27 ≈ 13.294 . . . ohms

This, in turn, is in series with the 2.5 ohms in the bottom branch, bringing the total circuit resistance to about 15.794 ohms, or 537/34 ohms.

The total source current is then ...

  I = V/R = (15 v)/(537/34 Ω) = 170/179 A ≈ 0.9497 A

_____

Alternate solutions

Alternatively, you can write and solve three node or loop equations for this circuit. For example, the equations for CCW loop currents, with I1 as the bottom loop, could be written in augmented matrix form as ...

  [tex]\left[\begin{array}{ccc|c}27.5&-10&-15&-15\\-10&55&-25&0\\-15&-25&50&0\end{array}\right][/tex]

The result is the same.

You have a 25 W and a 100 W bulb at home. When you connect one or the other, which bulb carries the greater current

Answers

Answer:

100 w bulb has more current.

Explanation:

P=V^2/R.

when velocity is constant power is inversly proportional to resistence, so 25 W will have an hogher resistance tjan a 100 w bulb.

P=VI

when v is constant, power is directly proportional to I. hence, 100 w bulbs will carry more current.

When you connect one or the other, the bulb that's connected carries more current than the one that's not connected.

When you connect BOTH of them, the 100W bulb carries more current than the 25W one.

Given the force diagram of the basketball, what can you tell about the basketball motion?

Answers

Newton's laws allow to find the result for the movement of the basketballl:

On the vertical axis the ball is on the ground. On the horizontal axis the ball is accelerating in the direction of the pushing force.

Newton's laws establish the relationship between the forces on objects:

The 1st law states that if the net force is zero the object is stationary or with constant speed. The 2nd law gives a relation of the force with the mass and the acceleration of the body. The 3rd. Law states that the force appears in pairs, one on each body with the same magnitude, but in the opposite direction.

Let's apply these principles to the ball's motion diagram.

The two vertical forces are in the opposite direction, one is due to the weight of the body and the other is the attraction of the earth to the support of the ball, they are of equal magnitude, not their action-reaction force and reluctant because it is applied to the same body

       In conclusion we can say that the ball is on the ground.

The two horizontal forces are in the opposite direction, the thrust force is greater than the friction therefore using Newton's second law the ball must be accelerating in the direction of the thrust force.

       In conclusion we can say that the ball is accelerating in the direction of the pushing force.

In conclusion using Newton's laws we can find the result for the motion of the basketball:

On the vertical axis the ball is on the ground. On the horizontal axis the ball is accelerating in the direction of the pushing force.

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3. What can you infer about the position of the galaxies 100 million years before this telescope photo was taken

Answers

The galaxies are in constant motion so it can be inferred that their position will not be the same as a hundred million years ago.

A galaxy is a term to refer to the set of stars, gas clouds, planets, cosmic dust, dark matter, and energy gravitationally united in a more or less defined structure in the universe.

Galaxies are in constant motion because the elements that make them up are not static at any time; The galaxies rotate around the center of the galaxy. If they were still, the gravitational attraction would cause them to immediately fall towards the center of the galaxy: it is the same that would happen to the Earth and the other planets if they stopped rotating around the Sun, they would fall towards the Sun.

According to the above, it can be inferred that the galaxies after a while have moved from the place where they were last seen.

Note: This question is incomplete because there is some missing information. However, I can answer based on my general prior knowledge.

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URGENTLY NEED HELP!!!!!!


the stretch of a spring and the force it exerts are inversely proportional.

Select one:

O True
O False​

Answers

Answer:

False.

Explanation:

Which is the best way to avoid plagiarism? O use more than one source from your research O repeat information from your sources O present a topic in your own words O understand your topic before you begin writing​

Answers

Answer:

O present a topic in your own words

Explanation:

Plagiarism is using someone else's words or work without giving them proper credit. Presenting a topic in your own words means you are not copying anyone.

Answer:

present a topic in your own words

Explanation:

a mass of 7.5kg has a weight of 30n on a certain planet calculate the acceleration due to gravitt on this planet

Answers

Answer:

Acceleration due to gravity on a certain planet = 4 m/s²

Explanation:

According to the question,

Weight = 30 N

Mass = 7.5 kg

Let acceleration due to gravity be 'a'

Formula:

Weight = Mass × Acceleration due to gravity

30 = 7.5 × a

a = 30/7.5

a = 4 m/s²

A 30.0-g object moving to the right at 20.5 cm/s overtakes and collides elastically with a 13.0-g object moving in the same direction at 15.0 cm/s. Find the velocity of each object after the collision. (Take the positive direction to be to the right. Indicate the direction with the sign of your answer.)

Answers

Let m₁ and m₂ be the masses of the two objects, and v₁ and v₂ their initial velocities. So

m₁ = 30.0 g = 0.0300 kg

m₂ = 13.0 g = 0.0130 kg

v₁ = + 20.5 cm/s = 0.205 m/s

v₂ = + 15.0 cm/s = 0.150 m/s

and we want to find v₁' and v₂', the final velocities of either object after their collision.

Momentum is conserved throughout the objects' collision, so that

m₁v₁ + m₂v₂ = m₁v₁' + m₂v₂'

where v₁' and v₂' are the first and second object's velocities after the collision.

Kinetic energy is also conserved, so that

1/2 m₁v₁² + 1/2 m₂v₂² = 1/2 m₁(v₁')² + 1/2 m₂(v₂')²

or

m₁v₁² + m₂v₂² = m₁(v₁')² + m₂(v₂')²

From the first equation (omitting units), we have

0.0300 • 0.205 + 0.0130 • 0.150 = 0.0300 v₁' + 0.0130 v₂'

0.0810 = 0.0300 v₁' + 0.0130 v₂'

81 = 30 v₁' + 13 v₂'

From the second equation,

0.0300 • 0.205² + 0.0130 • 0.150² = 0.0300 (v₁')² + 0.0130 (v₂')²

0.00155 ≈ 0.0300 (v₁')² + 0.0130 (v₂')²

1.55 ≈ 30 (v₁')² + 13 (v₂')²

Solving both equations simultaneously gives two solutions, one of which corresponds to the initial conditions. The other yields

v₁' ≈ + 0.172 m/s

and

v₂' ≈ + 0.227 m/s

The tires of a car make 77 revolutions as the car reduces its speed uniformly from 95.0 km/h to 65.0 km/h. The tires have a diameter of 0.90 m.
If the car continues to decelerate at this rate, how far does it go? Find the total distance.

Answers

Answer:

Explanation:

95.0 km/hr = 26.39 m/s

65 km/hr = 18.06 m/s

Circumference of a tire is 0.9π m

77 revolutions is a distance of

77(0.9π) = 69.3π m

v² = u² + 2as

a = (v² - u²) / 2s

a = (18.06² - 26.39²) / (2(69.3π))

a = -0.85 m/s²

s = (v² - u²) / 2a

s = (0² - 26.39²) / 2(-0.85)

s = 409 m

Two objects are being lifted by a machine. One object has a mass of 2 kg, and is lifted at a speed of 2
m/s. The other has a mass of 4 kg and is lifted at a rate of 3 m/s.
a. Which object has more kinetic energy while it is being lifted?

Answers

Answer:

Kinetic energy = (1/2) (mass) (speed²)

First object: (1/2) (2 kg) (2 m/s)² = 4 joules .

Second object: (1/2) (4 kg) (3 m/s)² = 18 joules .

The second object had more kinetic energy than the first one had.

Explanation:

Answer:

Kinetic energy = (1/2) (mass) (speed²)

First object: (1/2) (2 kg) (2 m/s)² = 4 joules .

Second object: (1/2) (4 kg) (3 m/s)² = 18 joules .

The second object had more kinetic energy than the first one had.

During a picnic, you and two of your friends decide to have a three-way-tug-of-war, with three ropes in the middle tied into a knot. Roberta pulls to the west with 277 N of force; Michael pulls to the south with 603 N. a) With what force should you pull to keep the knot from moving

Answers

Answer:

Explanation:

I'm not 10% sure but i think that if you were to do:

603 + 277 = 880

1000 - 880 = 120

So to keep it from moving, i think you would need to pull with a force of 120N

The force with which it should be pulled to keep the knot from moving is 663.58 N.

What is Newton's third law ?

Newton's third law states that, for every action, there is an equal and opposite reaction.

Here,

Force exerted by Roberta, F₁ = 277 N

Force exerted by Michael, F₂ = 603 N

Since, Roberta is pulling to the west and Michael is pulling towards the south, the angle between the forces applied by them is 90°.

The force needed to keep the knot from moving is the resultant force of these two forces.

Therefore, the resultant force,

Fₙ = √F₁² + F₂²

Fₙ = √(277)² + (603)²

Fₙ = 663.58 N

Hence,

The force with which it should be pulled to keep the knot from moving is 663.58 N.

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What's the kinetic energy of an object that has a mass of 12 kilograms and moves with a velocity of 10 m/s?

Answers

Answer:

600 J

Explanation:

Given,

Mass (m) = 12 kgVelocity (v) = 10 m/s

As we know,

Kinetic Energy,

[tex] E_{k} \: = \frac{1}{2} m {v}^{2} [/tex]

Therefore ,

Kinetic energy of the object is,

[tex] = \frac{1}{2} \times 12 \: kg \times 10 \: m {s}^{ - 1} \times 10 \: m {s}^{ - 1} [/tex]

(On dividing 12 by 2 we get 6)

= (6 × 10 × 10) J [As 'J' stands for 'joule']

= 600 J (Ans)

A cylindrical region of radius R contains a uniform magnetic field parallel to its axis. The field is zero outside the cylinder. If the magnitude of the field is changing at the rate dB/dt, the electric field induced at a point 2R from the cylinder axis is:

Answers

The magnitude of the induced electric field is (RdB/dt)/4

The induced electric field is gotten from

-∫E.dl = dФ/dt where E = induced electric field, dl = path length vector, Ф = magnetic flux through cylindrical region = AB where A = area of magnetic flux = πR² where R = radius of cylindrical region and B = magnetic field.

So, -∫E.dl = dФ/dt

-∫E.dl = dAB/dt

-∫Edlcos0 = AdB/dt (where E.dl = Edlcos0 = Edl since E and dl are parallel to each other.)

So -∫Edl = πR²dB/dt

-E∫dl = πR²dB/dt (∫dl = 2πr since the integral is the circumference of the path)

-E(2πr) = πR²dB/dt (we integrate dl from r = 0 to 2R)

-E2π(2R - 0) = πR²dB/dt

-E4πR= πR²dB/dt

E = πR²dB/dt ÷ 4πR

E = -(RdB/dt)/4

So, the magnitude of the induced electric field is (RdB/dt)/4

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PLZ HURRY
When you hold a racquet and swing your arm toward the ball, there are two kinds of resistance working against your muscles—the ______ and the ______.

A.
racket, air

B.
air, ball

C.
ball, net

D.
air, racket

Answers

Answer:

It should just be A

Explanation:

I dont see the difference between these 2 but ill choose A and update you

Answer:

A: racket, air

Explanation:

If work stays the same and the distance is increased, then less force is needed to do the work.
True
False

Answers

Not sure what “work” defines but from my understanding I’d go with false.

Answer:

False

Explanation:

This is because the work is the same so the force won't change

An object is at rest on a tabletop. Earth pulls downward on this object with a force equal in magnitude to mg. If this force serves as the action force, what is the reaction force in the action–reaction pair?

Answers

Answer:

Equal reaction from the pair in every action there's an equal and opposite reaction

The item will keep moving at a consistent speed if the object is at rest on a tabletop. Earth pulls downward on this object with a force equal in magnitude to mg.

What is gravitational force?

All mass-bearing objects are attracted by gravitational force. Because it consistently attempts to bring masses together rather than push them apart, the gravitational force is referred to as attractive.

As we know, the gravitational force is given by:

[tex]\rm F = \dfrac{Gm_1m_2}{r^2}[/tex]

Where G is the gravitational constant.

m1 and m2 are masses.

r is the distance between the masses.

It is given that:


An object is at rest on a tabletop. Earth pulls downward on this object with a force equal in magnitude to mg.

As we know,

An object is at rest on a tabletop. Earth pulls downward on this object with a force equal in magnitude to mg and the item will keep moving at a consistent speed.

Thus, the item will keep moving at a consistent speed if the object is at rest on a tabletop. Earth pulls downward on this object with a force equal in magnitude to mg.

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A phone is dropped from the roof of the school building. The building is 13.2 meters high. How long was the phone in the air before it crashed on the ground?

Answers

Answer:

5scs

Explanation:

phones fall fast so i guessed

electric field due to on the surface of the charge sphere​

Answers

Explanation:

static electricity draws energy

Pls help me with this one :)) ​

Answers

Answer:

Row A is correct

Explanation:

both conduction and convection require mass to complete any heat transfer. A vacuum contains no mass

A grinding wheel is a uniform cylinder with a radius of 8.50 cm and a mass of 0.380 kg. Calculate (a) its moment of inertia about its center, and (b) the applied torque needed to accelerate it from rest to 1750 rpm in 5.00 s. Take into account a frictional torque that has been measured to slow down the wheel from 1500 rpm to rest in 55.0 s.

Answers

Hi there!

(A)

A grinding wheel is the same as a disk, having moment of inertia of:

[tex]I = \frac{1}{2}MR^2[/tex]

Plug in the given mass and radius (REMEMBER TO CONVERT) to find the moment of inertia:

[tex]I = \frac{1}{2}(0.380)(0.085)^2 = 0.00137 kgm^2[/tex]

(B)

We can use the rotational equivalent of Newton's Second Law to calculate the needed torque:

Στ = Iα = τ₁ - τ₂

Begin by solving for the angular acceleration. Convert rpm to rad/sec:

[tex]\frac{1750r}{min} * \frac{1 min}{60 s} * \frac{2\pi rad}{1 r} = 183.26 rad/sec[/tex]

Now, we can use the following equation:

ωf = wi + αt (wi = 0 rad/sec, from rest)

183.26/5 = α = 36.65 rad/sec²

τ = Iα = 0.0503 Nm

Since there is a counter-acting torque on the system, we must begin by finding that acceleration:

[tex]\frac{1500r}{min} * \frac{1 min}{60 s} * \frac{2\pi rad}{1 r} = 157.08 rad/sec[/tex]

ωf = wi + αt

-157.08/55 = α = -2.856 rad/sec²

τ₂ = Iα = 0.0039 Nm

Now, calculate the appropriate torque using the above equation:

[tex]\Sigma\tau = \tau_1 - \tau_2[/tex]

[tex]\Sigma\tau + \tau_2 = \tau_1[/tex]

[tex]0.0503 + 0.0039 = \large\boxed{0.054 Nm}[/tex]

5 What is the maximum speed at which a car round a curve of 25m radius on a level road if the coefficient of static friction between the tires and the road is 0.80?​

Answers

Hi there!

On a level road:

∑F = Ff (Force due to friction)

The net force is the centripetal force, so:

mv²/r = Ff

Rewrite the force due to friction:

mv²/r = μmg

Cancel out the mass:

v²/r = μg

Solve for v:

v = √rμg

v = √(25)(9.81)(0.8) = 14.01 m/s

2. Jason rode his bike 10 miles and only rode for 2 hours how fast was he going?

Answers

Answer:

5 miles per hour.

Explanation:

10miles / 2hours = 5 mph

Heat is transferred from molecules with more kinetic energy to molecules with _________kinetic energy.

Answers

Answer:

less

Explanation:

heat travels from hotter to colder object. hotter object has more kinetic energy.

WILL MARK BRAINLIEST

1. What is the difference between distance and displacement?
A. Distance is measured in feet. Displacement is measured in meters

B. Distance is the difference between how quickly you move between two points. Displacement is the average of that motion

C. Distance is a measure of length of travel. Displacement is the measure of the time it takes to move that length

D. Distance is the length of travel. Displacement is the straight line distance between the starting point and the ending point

2. When forces are in opposite directions, they subtract from one another
A. True
B. False

3. When two forces are in opposite directions, and they are the exact same magnitude, the forces will
A. Subtract from each other
B. Cancel Out
C. Go on Infinitely
D. eventually reach equilibrium

4. Acceleration is a change in motion over time
True or False

Answers

Answer:

1. C

2. True

3. D

4. True

Explanation:

While distance refers to “how much land an object has traversed throughout its journey,” displacement measures “how far an object is out of place.” In this post, let's look at the difference between distance and displacement. Thus, option C is correct.

What are the distance and displacement?

Displacement and distance are two distinct ideas. The total distance travelled is larger than the displacement between those two points if an object changes direction while travelling.

Distance is the length of any path connecting any two places. Displacement is the straight-line distance between any two points when calculated along the shortest route.

Therefore, The direction is ignored when calculating distance. The direction is accounted for in the displacement calculation.

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*graph is below*

1. What is Peter’s total distance traveled? What is Peter's displacement?

2. Is there a time when Peter is not moving? If so, when?

Answers

The total distance covered is 24 Km and Peter was not moving between the points marked 10 mins and 30 mins on the graph. His displacement according to the graph is zero.

The distance time graph shows the distance covered plotted on the vertical axis against the time taken plotted on the horizontal axis. Using this graph, the total distance covered can easily be obtained.

The total distance covered is 12 km + 12 km since equal distance was covered to and fro. Hence the total distance covered is 24 km. Perter was not moving between the points marked 10 mins and 30 mins on the graph.

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Short, difficult activities that push your body are called
A.
aerobic activity
B.
anaerobic activity
C.
muscle strength
D.
exercise

Answers

Answer:

B. is your answer

Explanation:

Have a good day

Sincerly, lipor

Short, difficult activities that push your body are called anaerobic activities.  Option b is correct

They are high-intensity exercises that do not require oxygen and primarily use stored energy sources within the muscles. Examples include weightlifting or sprinting.

Short, difficult activities that push your body are called anaerobic activity. Anaerobic activities are high-intensity exercises that do not require oxygen and primarily use stored energy sources within the muscles, such as weightlifting or sprinting. These activities help build muscle strength and improve power and speed.

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