You see a train that is moving toward you and sounding its
whistle at a constant frequency. Compared to the sound
produced by the whistle, the wavelength of the sound
observed by you is

Answer:

the required distance is 89.125 m

Explanation:

Given the data in the question;

we know that, sound intensity B in decibels of sound is;

β(dB) = 10log₁₀( [tex]I[/tex] / [tex]I_0[/tex] )

where intensity [tex]I[/tex] = power / area carried by wave

[tex]I_0[/tex] = 10⁻¹² W/m² { minimum threshold intensity }

Now,

intensity [tex]I[/tex] = power / area carried by wave = P/A = P/4πr² { spherical  }

given that; β = 80.0 dB and P = 10 W

so

β(dB) = 10log₁₀( [tex]I[/tex] / [tex]I_0[/tex] )

we substitute

80 = 10log₁₀( P / 4πr²× [tex]I_0[/tex])

80 = 10log₁₀( 10 / 4πr²× 10⁻¹² )

8 = log₁₀(10) - log₁₀( 4πr²× 10⁻¹² )  

8 = 1 - log₁₀( 4πr²× 10⁻¹² )

8 - 1 = -log₁₀( 4πr²× 10⁻¹² )

7 = -log₁₀( 1.2566 × 10⁻¹¹ × r² )

7 = -[ log₁₀( 1.25 × 10⁻¹¹) + log₁₀( r² ) ]

7 = -[ -10.9 + log₁₀( r² ) ]

7 = 10.9 - log₁₀( r² )

-log₁₀( r² ) = 7 - 10.9

-log₁₀( r² )  = - 3.9

log₁₀( r² ) = 3.9

2log₁₀r = 3.9

log₁₀r  = 3.9 /2

log₁₀r = 1.95

r = 89.125 m

Therefore, the required distance is 89.125 m

Answer:

Option C: Third Class

Explanation:

This is third class because the effort or the input force is in the middle between the fulcrum and the load.

To solve this, we must be knowing each and every concept related to lever.  Therefore,  due to the effort or input force being in the center between the edge as well as the load, the supplied lever is of 3rd class. The correct option is option C.

A lever is a basic device that consists of a beam or stiff rod located at a set tight, or edge. It is used to apply force to a load and often offers a mechanical advantage.

A stiff object that can rotate about a spot on itself is called a lever. The three types of levers are categorized according to where the edge, weight, and effort are located. Due to the effort or input force being in the center between the edge as well as the load, the supplied lever is of  3rd class.

Therefore,  the correct option is option C.

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Explanation:

Potential energy=MGH

100=3×10×H.

H=100/30

H=3.40m

Answer:

A. Increases

Explanation:

Mark as Brainliest

Answer:

a. ε = 21,014sin(120πt) V

b. 0.476cosec(120πt)  

Explanation:

a. Induced emf

We know the induced emf, ε = -dΦ/dt where Φ = magnetic flux through coil = NABcosθ where N = number of turns of coil =, 100, A = area of coil = 10 ft × 6 ft = 60 ft² = 60 × 1 ft² = 60 × (0.3048)² m² = 5.574 m², B = magnetic field strength = 0.1 T and θ = angle between B and normal to A = ωt.

So, Φ = NABcosθ = 100 × 5.574 m² × 0.1 T cosθ  = 55.74cosθ Tm²

So, ε = -dΦ/dt = ε = -d(55.74cosθ Tm²)/dt = -d(55.74cosθ Tm²)/dθ × dθ/dt = -55.74 ×(-sinθ) Tm²)/dθ × ω (ω = dθ/dt = angular frequency of shaft = 2πf where f = frequency of rotor = 60 Hz )

ε = 55.74sinθ Tm²) × 2πf

ε = 55.74sinθ Tm²) × 2π(60 Hz)

ε = 6689πsinθ V

ε = 21,014sinθ V

ε = 21,014sinωt V

ε = 21,014sin(2πft) V

ε = 21,014sin(2π(60 Hz)t) V

ε = 21,014sin(120πt) V

b. Current in coil

Since power P = Iε where I = current and ε = induced emf = 21,014sinθ V.

Since power, P = 10 kW = 10000 W

I = P/ε

= 10000 W/21,014sinθ V

= 0.476/sinθ

= 0.476cosecθ

= 0.476cosecωt

= 0.476cosec(120πt)  

The maximum current is obtained when θ = 90°

I =  10000 W/21,014sin90 V

I = 10000 W/21,014 V

I = 0.476 A

I = 476 mA

Answer:

D

Explanation:

D ok ok ok ok bye

The correct statement is that the alcohol has lower boiling point than water. The correct option is B.

At the boiling point, the pressure exerted by the surroundings on a liquid equals the pressure exerted by the liquid's vapor, under this condition, adding heat outcomes in the transformation of the liquid into its vapor without raising the temperature.

The boiling point of alcohol is low. Because there is less hydrogen bonding between ethanol molecules than between water molecules.

The ethanol requires less energy to vaporize than water, and water has a higher boiling point than ethanol.

The boiling point of a liquid can be known by utilizing the capillary method, that encompasses placing an inverted capillary in the liquid of interest as well as heating it.

Thus, the correct option is B.

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Answer:

c

Explanation:

the gas pedal gives the engine the fuel it needs to give the car the power to go

Answer:

In fission, energy is gained by splitting apart heavy atoms, for example uranium, into smaller atoms such as iodine, caesium, strontium, xenon and barium, to name just a few. However, fusion is combining light atoms, for example two hydrogen isotopes, deuterium and tritium, to form the heavier helium.

Explanation:

I hope this helped you

(Sorry If it didn't)

Answer:

C

Explanation:

edge 2020... Using elimination it's the only one that makes sense.

The statement third "an increase in the distance between the objects causes a greater change in the gravitational force than the same increase in mass" is correct.

The gravitational force is a force that attracts all mass-bearing objects. The gravitational force is referred to as attractive because it always strives to pull masses together rather than pushing them apart.

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.

From the data given in the table, shows that:

The gravitational force is indirectly proportional to the square of the distance.

Thus, the statement third "an increase in the distance between the objects causes a greater change in the gravitational force than the same increase in mass" is correct.

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Explanation:

It will be B.Its particles have no kinetic energy.

Answer:

[tex]\boxed {\boxed {\sf D.\ 6.4\ m/s^2}}[/tex]

Explanation:

We need to find the acceleration of the 2 kilogram object. Let's complete this in 2 steps.

First, we can find the force of the first, 8 kilogram object.

According to Newton's Second Law of Motion, force is the product of mass and acceleration.

[tex]F=m \times a[/tex]

The mass of the object is 8 kilograms and the acceleration is 1.6 meters per square second.

Substitute these values into the formula.

[tex]F= 8 \ kg * 1.6 \ m/s^2[/tex]

Multiply.

[tex]F= 12.8 \ kg*m/s^2[/tex]

Now,  use the force we just calculated to complete the second part of the problem. We use the same formula:

[tex]F= m \times a[/tex]

This time, we know the force is 12.8 kilograms meters per square second and the mass is 2 kilograms.

Substitute the values into the formula.

[tex]12.8 \ kg*m/s^2= 2 \ kg *a[/tex]

Since we are solving for the acceleration, we must isolate the variable (a). It is being multiplied by 2 kg. The inverse of multiplication is division. Divide both sides of the equation by 2 kg.

[tex]\frac {12.8 \ kg*m/s^2}{2 \ kg}= \frac{2\ kg* a}{2 \ kg}[/tex]

[tex]\frac {12.8 \ kg*m/s^2}{2 \ kg}=a[/tex]

The units of kilograms cancel.

[tex]\frac {12.8}{2}\ m/s^2=a[/tex]

[tex]6.4 \ m/s^2=a[/tex]

The acceleration is 6.4 meters per square second.

Answer:

It can travel in various wavelengths. brainliest?

Explanation:

The evidence that reveals about the light is that  It can travel in various wavelengths.

It is the wave property that should be blending of the wave related to the corners.

At the time when the wave is bending so it passed via the openings.

Also, the light diffracted via the small slits and it should be shown to arise in the water waves and the sound waves.

hence, the first option is correct.

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Answer:

upward

Explanation:

In the electromagnetic system of force if the direction of motion of proton does not changes it means that the electric and magnetic forces are such a ways that they are cancelling each other's effect.

Since, electric field lines will exert a force on the proton to the west, hence, the magnetic force must force it to the east. It is well known that magnetic force acts perpendicular to the direction of magnetic field.  magnetic field should point upward direction.

B. The energy transformation that is correct is From C to D, kinetic energy is transformed into gravitational potential energy.

The law of conservation of energy states that energy can neither be created nor destroyed but can be transformed from one form to another.

Energy transformation in the pendulum;

Thus, the energy transformation that is correct is From C to D, kinetic energy is transformed into gravitational potential energy.

option B is the correct answer.

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Answer:

B is Correct

Explanation:

From C to D, kinetic energy is transformed into gravitational potential energy.

Answer:

 y_lower = 0.915 m,   y_superior = 1,905 m

Explanation:

In this exercise we use the law of reflection for a flat mirror.

         θ’= θ

To see the feet of the person a ray of light that part of them must reach the bottom of the mirror and its reflection has to reach the eyes.

As the law of reflection the incident and reflected angles are equal, the distance from the floor to the point where the two rays (incident and reflected) touch the mirror must be symmetrical, oses from the floor

           y = 1.83 / 2

           y = 0.915 m

To see the head, a ray of light that comes from the tip of the head and is reflected in the mirror must reach the eyes. As the head is 0.15 m above the eyes and the incident and reflected rays have the same angle, the mirror must be at half the height, that is, the mirror is 0.075 m below the tip of the head.

In summary

* the bottom of the mirror is 0.915 m from the ground

* the top of the mirror is at 1.83 + 0.075

                 y_superior = 1,905 m

ground

Answer: When a ray of light approaches a smooth polished surface and the light ray bounces back, it is called the reflection of light. The incident light ray which lands upon the surface is said to be reflected off the surface. The ray that bounces back is called the reflected ray.

Have a great day and stay safe !

Answer:

Alternating voltage leads to electromagnetic induction which is necessary for the transformer to work.

Explanation:

According to Oxford dictionary; an alternating current is "an electric current that reverses its direction many times a second at regular intervals".

A transformer works on the principle of electromagnetic induction. A transformer requires an alternating current which can create a changing magnetic field leading to induced voltage in the coil.

Hence, a transformer requires alternating voltage because alternating voltage leads to electromagnetic induction which is necessary for the transformer to work.

Answer:

force on the electron is upwards

Explanation:

The magnetic force is given by the relation

        F = q v x B

the bold indicates vectors, we can write the module of this expression

        F = q v  B sin θ

the direction of the force is given by the right hand rule.

If we have a positive charge, the flea points in the direction of velocity, in this case towards the inside of the page.

fingers extended in the direction of the magnetite field, in our case to the right and

the palm gives the direction of the force for a positive charge, for a negative charge it is in the opposite direction. The palm points downwards, so the force on the electron is upwards

Explanation:

Extrusive rocks may have a few grains that are large enough to see, but most of them will be too small to see individual minerals. ... The individual mineral grains are almost too small to see. Some extrusive rocks cool so quickly that they do not form any grains. Instead, they form a natural glass.

Answer:

D

Explanation:

Answer:

ω = 0.05 rad/s

Explanation:

In order to produce the acceleration equal to the acceleration due to gravity at the surface of Earth, the centripetal acceleration must be equal to the value  of g:

[tex]a_c = g\\g = \frac{v^2}{r}\\\\but,\ v=r\omega\\therefore,\\\\g = \omega^2r\\\\\omega = \sqrt{\frac{g}{r}}[/tex]

where,

ω = angular speed = ?

g = acceleration due to gravity on the surface of the Earth = 9.81 m/s²

r = radius of cylinder = 8 km/2 = 4 km = 4000 m

Therefore,

[tex]\omega = \sqrt{\frac{9.81\ m/s^2}{4000\ m}}[/tex]

ω = 0.05 rad/s

Answer:

Explanation:

Density = Mass / Volume = 850 / 40*10*5 = 0.425 g /cm^3

Answer:

Option A

Explanation:

In this experiment, when balloon is rubbed on the chair electrons are transferred from the hair to the surface of the balloon thereby making balloon negatively charged and hair positively charged. When two negatively charged balloon are brought close to each other, they repel while when balloon is brought closer to the hair, they attract each other

Hence, option A is correct

Answer

the wavelength is 90

Explanation:

Answer:

Negative electric charges