To hear a train approaching from far away, why is it more convenient to put the ear to the track?

Answers

Answer 1

Answer:

If you want to hear a train approaching from far away,it is more convenient to put the ear to the track.This is because sound can travel through railway track (solid ) faster than through air.


Related Questions

Un semáforo de 80N cuelga del punto medio de un cable de 30m tendido entre 2 postes. Halle la tensión en cada segmento del cable si éste tiene un pandeo que lo hace descender una distancia vertical de 1m

Answers

Answer:

T1 = T2 = 602.33 N

Explanation:

I attached an image of the forces diagram below.

The x component of the forces for this cases is:

[tex]\Sigma F_x=T_1cos\theta-T_2cos\theta=0\\\\T_1cos\theta=T_2cos\theta\\\\T_1=T_2[/tex]

And the y components:

[tex]\Sigma F_y=T_1sin\theta+T_2sin\theta-W=0\\\\T_1=T_2=T\\\\\Sigma F_y=2Tsin\theta=W\\\\T=\frac{W}{2sin\theta}[/tex]

The angle is calculated by using the information about the length of the cable and the vertical distance of the traffic light:

[tex]\theta=tan^{-1}(\frac{1}{15})=3.81\°[/tex]

Thus, you obtain:

[tex]T=\frac{80N}{2(sin3.81\°)}=601.33N[/tex]

hence, the tension in both segments of the cable is 602.33 N

A rectangular loop of wire that can rotate about an axis through its center is placed between the poles of a magnet in a magnetic field with a strength of 0.40 T. The length of the loop L is 0.16 m and its width w is 0.040 m. What is the magnetic flux through the loop when the plane of the loop is perpendicular to the magnetic field?

Answers

Explanation:

hope this helps you...........

The magnetic flux through the loop when the plane of the loop is perpendicular to the magnetic field is 0.0256 Weber.

What is magnetic field?

The magnetic field is the region of space where a charged object experiences magnetic force when it is moving.

The formula for magnetic flux is given as;

φ = BAcosθ

Given, a rectangular loop of wire that can rotate about an axis through its center is placed between the poles of a magnet in a magnetic field with a strength of 0.40 T. The length of the loop L is 0.16 m and its width w is 0.040 m.

Area of the loop = L x w

                        A  = 0.16 x 0.040 m

                         A = 0.0064 m²

So, flux will be

φ = 0.4 x  0.0064 x cos90°

φ = 0.00256 Wb

Thus, magnetic flux through the loop when the plane of the loop is perpendicular to the magnetic field is 0.0256 Weber.

Learn more about magnetic field.

https://brainly.com/question/14848188

#SPJ2

The rigid beam is supported by the three suspender bars. bars ab and ef are made of aluminum and bar cd is made of steel. if each bar has a cross-sectional area of 450 mm2, determine the maximum value of p if the allowable stress is (σallow)st = 200 mpa for the steel and ( σallow)al = 150 mpa for the aluminum. est = 200 gpa and eal = 70 gpa.

Answers

Answer:

Pmax = 67.5 KN

Explanation:

We need to calculate the maximum allowable value of P for both aluminum and steel bars.

FOR STEEL BARS:

Since,

(σallow)st = (Pmax)st/A

where,

(σallow)st = maximum allowable stress of steel bar = 200 MPa = 2 x 10⁸ Pa

A = Cross-sectional area of steel bar = 450 mm² = 0.45 x 10⁻³ m²

(Pmax)st = Maximum allowable force for steel bar = ?

Therefore,

2 x 10⁸ Pa = (Pmax)st/0.45 x 10⁻³ m²

(Pmax)st = (2 x 10⁸ Pa)(0.45 x 10⁻³ m²)

(Pmax)st = 9 x 10⁴ N = 90 KN

FOR Aluminum BARS:

Since,

(σallow)al = (Pmax)al/A

where,

(σallow)al = maximum allowable stress of Al bar = 150 MPa = 1.5 x 10⁸ Pa

A = Cross-sectional area of Aluminum bar = 450 mm² = 0.45 x 10⁻³ m²

(Pmax)al = Maximum allowable force for Aluminum bar = ?

Therefore,

1.5 x 10⁸ Pa = (Pmax)al/0.45 x 10⁻³ m²

(Pmax)al = (1.5 x 10⁸ Pa)(0.45 x 10⁻³ m²)

(Pmax)al = 6.75 x 10⁴ N = 67.5 KN

Since,

(Pmax)al < (Pmax)st

Therefore,

The maximum allowable force will be:

Pmax = (Pmax)al

Pmax = 67.5 KN

How are the electric field lines around a positive charge affected when a second positive charge is near it?

Answers

Answer:Because it likes to repel and attract opposites

When the Sun’s radiant energy falls on Earth’s oceans, it causes water to change state by evaporating. Which form of energy does water vapor have?

Answers

Answer:

water vapor is a type of gas

Explanation:

all gas are in air state of form

hope this helps

Answer:

chemical potential energy

Explanation:

When the sun's radiant energy falls on Earth's oceans, it causes water to change state by evaporating. The form of energy water vapor have is chemical potential energy. when heat energy of sun falls on water surface, its state change from liquid to gas. This gas rises above in the form of water vapor. Its a chemical change. If this vapor get condense/ cool, it will turn into liquid again. We can say that vapor has potential to transform into water again. Thus, the energy stored in water vapor is called chemical potential energy.

Choose the best definition for velocity
1. How fast something is going
2. Speed in a certain direction
3. Which direction something is going
4. Something speeding up

Answers

It’s speed in a certain direction.

O rază de lumină cade sub un unghi de incidență i=30⁰ pe o suprafață

plană ce separă două materiale transparente cu indici de refracție n 1 = 1,60

și n 2 = 1,40.

Calculați unghiul de refracție (din mediul cu indicele de refracție mai mic).

Sugestie: sin 30⁰ = ½.

Answers

Answer:

Explanation:

The question in english is:

A ray of light falls under an angle of incidence of 30 degrees on a flat surface that separates two transparent materials with indexes of refractions 1.60 and 1.40, respectively.

Calculate the angle of refraction (from the environment with the lower index of refraction)

Solution

According to Snell's Law :

[tex]n_{1}sin(\theta_{1})=n_{2}sin(\theta_{2})[/tex]

Where:

[tex]n_{1}=1.6[/tex]  is the first medium index of refraction

[tex]n_{2}=1.4[/tex]  is the second medium index of refraction

[tex]\theta_{1}=30\°[/tex]  is the angle of the incident ray

[tex]\theta_{2}[/tex] is the angle of the refracted ray

We need to find [tex]\theta_{2}[/tex] from the equation above,

[tex]\theta_{2}=sin^{-1}(\frac{n_{1}}{n_{2}}sin\theta_{1} )[/tex]

[tex]\theta_{2}=sin^{-1}(\frac{1.6}{1.4}sin(30\°)[/tex]

[tex]\theta_{2}=34.84\°[/tex]

Therefore, the angle of refraction is 34.84°

A 1500kg car moves foward with 30kg•m/s of momentum. What is its velocity
Select one
•-1470m/s
•0.02m/s
•45,000m/s
•-50m/s

Answers

Answer:

v = 30 /1500= 0.02 m/s

................

A popcorn-maker transfers 250 J of energy into other energy stores every second. What is its power?

Answers

Answer: 250 watts

Explanation:

energy=250J

Time=1 sec

Power=energy ➗ time

Power=250 ➗ 1

Power=250

Power is 250 watts

The Power will be "250 Watts".

According to the question,

Energy,

250 J

Time,

1 second

The formula,

→ [tex]Power =\frac{Energy}{Time}[/tex]

By substituting the values, we get

              [tex]= \frac{250}{1}[/tex]

              [tex]= 250 \ Watts[/tex]

Thus the above approach is right.

Learn more about power here:

https://brainly.com/question/23443372

30
. Which of the following represents the
statement "The difference of two square
numbers is positive​

Answers

Answer:

In mathematics, the difference of two squares is a squared (multiplied by itself) number subtracted from another squared number. Every difference of squares may be factored according to the identity. in elementary algebra.

Explanation:

which factors affect the strength of magnetic field around current carrying wire?

Answers

Explanation:

The expression for the magnetic field around the current carrying wire is given by :

[tex]B=\dfrac{\mu_o I}{2\pi r}[/tex]

Here,

I is electric current and r is distance from the wire.

The factors affect the strength of magnetic field around current carrying wire are :

Electric currentDistance from wire

A potential difference of 24 V is applied to a 150-ohm resistor. How much current flows through the resistor?​

Answers

Given :- A resistor of 150 ohm, hence Resistance (R) = 150 ohm

Potential Difference (v) = 24 V

Current (I) = ?

V = IR

24 = I × 150

I = 24/150

I = 0.16 ampere

hope it helps!

The graph to the right represents the change in velocity of four cars over a period of 10 hours. Which line represents the car with the greatest acceleration?
A. A C. C
B. B D. D
Please help me

Answers

Answer:

there is an option for uploading the pic of a diagram while posing any question on brainly. hope you use that feature of the app to upload graph of your question so that it can be well answered

Answer: It’s A!

Explanation: I took the test

In a step down transformer, voltage steps down. What factor must go up?

Answers

Answer:

A transformer that increases the voltage from primary to secondary (more secondary winding turns than primary winding turns) is called a step-up transformer. Conversely, a transformer designed to do just the opposite is called a step-down transformer.

Explanation:

plzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz mark me brainliest

A microwave oven uses a current of 0.45 Amps in a voltage of 120 Volts how much power does a microwave use?

Answers

Answer:

54 W

Explanation:

Power = Voltage* Current =V*I = 120V*0.45A =54 Watt

explain nuclear fusion briefly

Answers

Answer:

Nuclear fusion is the process in which two atomic nuclei are fused together into a larger single nucleus, releasing energy in the process. ... In proton-proton fusion, four hydrogen atoms are fused into a single helium-4 atom, releasing a lot of energy in the process.

Explanation:

Which happens during the day at the beach?

A. The water is warmer than the land, and air sinks over the water

B. The water is cooler than the land, and air sinks over the water

C. The water is warmer than the land, and air rises over the water

D. The water is cooler than the land, and air rises over the water

Answers

Answer:

c

Explanation:

not sure i think heating beach

2. A new racecar track is being created, and the owners want the cars to complete 10
miles in 7 laps. What does the diameter of the track have to be to meet their
requirements?

Answers

Answer:

0.45 miles

Explanation:

since, car will be running on the edge of track, distance covered in one lap by car will be equal to circumference of track.\

we will use value of pi as 22/7

Circumference for any circular shape is given by [tex]\piD[/tex][tex]\pi D[/tex]

Hence, in one lap [tex]\pi D[/tex] distance will be covered

in 7 laps [tex]7 \pi D[/tex] distance will be covered.

but is given that 7 laps should be equal to 10 miles

so 10 miles will be equal to [tex]7\pi D[/tex]

[tex]7\pi D= 10 \ miles\\=> 7*(22/7)* D= 10 \ miles\\=> 22D = 10 \ miles\\=> D = 10/22 \ miles\\=> D = 0.45 \ miles[/tex]

Thus, diameter of track will be 0.45 miles to meet the requirement.

Which of the following are two factors that determine speed?
a. acceleration and time
b. distance and time
c. velocity and time
d. motion and time

Answers

Answer:

B) Distance and Time

Explanation:

Equation for speed: S = D / T

Speed equals the distance you traveled divided by the amount of time it took to get to that destination.

The two factors which are required to determine the speed of a object are distance traveled by it and time taken by it.

What is speed?

The speed is the rate at which the total distance by a object is traveled in the time taken.

Speed of a object can be given as,

[tex]s=\dfrac{d}{t}[/tex]

Here, (d) is the distance traveled by the object and (t) is time taken but the object to cover that distance.

As the unit of the distance is measured in the meter and the time measure in the second. Thus the speed of a object is measured in the meter per second.

In the vehicles the speed of vehicle is also measured in the kilometre per hour or miles per hour.

Hence, the two factors which are required to determine the speed of a object are distance traveled by it and time taken by it.

Thus the option B is the correct option.

Learn more about the speed here;

https://brainly.com/question/359790

Only the sun and other stars in space generate these kinds of waves:

Answers

Answer:

Ultraviolet Waves.

Explanation:

The Sun emits waves called "Solar Waves", which have a wavelengths between 160 and 400 nanometers. According to the electromagnetic spectrum, these waves are defined as Ultraviolet, which have a frequency around the order of [tex]10^{16}[/tex], which is really intense and high energy.

Therefore, the answer is Ultraviolet Waves.

What causes atoms to bond together
?!?

Answers

Answer:

electrostatic attraction

Explanation:

Atoms form chemical bonds with other atoms when there's an electrostatic attraction between them. This attraction results from the properties and characteristics of the atoms' outermost electrons, which are known as valence electrons.

Electrostatic attraction

what is the function of strong nuclear forces

Answers

Answer:

The strong force binds quarks together in clusters to make more-familiar subatomic particles, such as protons and neutrons. It also holds together the atomic nucleus and underlies interactions between all particles containing quarks

Explanation:

PLEASE GIVE ME BRAINLIEST IF NEW IT SHOULD SAY MARK AS BRAINLIEST IF NOT YOULL HAVE TO WAIT A DAY AND BRAINLY WILL REMIND YOU

Kinetic friction is the frictional force needed to start an object at rest into
motion.
A. True
B. False

Answers

Answer:

b.false i think

Explanation:

i hope i am correct and helps you

Answer:false

Explanation:

I just did it

If the electrons in an atom were stationary, they would be ___ the nucleus

Answers

Answer:

Matter in the universe is made up of atoms, particles if electrons were to be stationary, they would have fallen into the nucleus because of electrostatic force acting on them destroying very existence of an atom we know.

An air-track glider attached to a spring oscillates between the 10.0 cm mark and the 61.0 cm mark on the track. The glider completes 11.0 oscillations in 31.0 s

Answers

Answer:

T = 2.82 seconds.

The frequency [tex]\mathbf{f = 0.36 \ Hz}[/tex]

Amplitude A = 25.5 cm

The maximum speed of the glider is [tex]\mathbf{v = 56.87 \ rad/s}[/tex]

Explanation:

Given that:

the time taken for 11 oscillations is 31 seconds ;

SO, the time taken for one oscillation is :

[tex]T = \frac{31}{11}[/tex]

T = 2.82 seconds.

The formula for calculating frequency can be expressed as :

[tex]f = \frac{1}{T}[/tex]

[tex]f = \frac{1}{2.82}[/tex]

[tex]\mathbf{f = 0.36 \ Hz}[/tex]

The amplitude is determined by using the formula:

[tex]A = \frac{d}{2}[/tex]

The limits that the spring makes the oscillations are from 10 cm to 61 cm.

The distance of the glider is, d = (61 - 10 )cm = 51 cm

Replacing 51 for d in the above equation

[tex]A = \frac{51}{2}[/tex]

A = 25.5 cm

The maximum speed of the glider is:

[tex]v = A \omega[/tex]

where ;

[tex]\omega = \frac{2 \pi}{T}[/tex]

[tex]\omega = \frac{2 \pi}{2.82}[/tex]

[tex]\omega = 2.23 \ rad/s[/tex]

[tex]v = A \omega[/tex]

[tex]v = 25.5 *2.23[/tex]

[tex]\mathbf{v = 56.87 \ rad/s}[/tex]

Heat pumps move heat from __________ to __________ areas & REQUIRES energy. *

A. cold, hot
B. hot, cold

What is the electrical power when the current is 20 amps and the voltage is 15 volts? *

A. 35 watts
B. 1.33 watts
C. 300 watts

Work is a transfer of matter. *

A. True
B. False

Answers

The correct answer to this question is false

The passage helps the reader to draw conclusions about which character's perspective? ºAlec ºAlice ºAlec's father ºAlec's mother

Answers

Answer:

I think it might be A: Alec but tell me if I'm wrong

Explanation:

Answer:

a

Explanation:

i did it on e d g e n u i t y



A man can lift a mass of 200kg onThe surface of the earth. what is the amount of mass he can lift on the surface of the moon?

Answers

Answer:

1,211.1 kg.

Explanation:

the force of gravity is less on the moon than on earth, so if the man can lift 200kg on earth, he could lift a greater amount on the moon because there is less resistance from gravity.

To know the amount of mass he can lift on the moon, we first need to know the amount of weight that is equivalent to those 200kg here on earth. This because the weight of the object is equal to the force that must be applied to lift it, and that force is applied by the man and it will be the same here and on the moon.

We calculate weight using the formula:

[tex]w=mg[/tex]

where [tex]w[/tex] is the weight of the object (the force with which the earth attracts the object) [tex]m[/tex] is the mass and g the acceleration of gravity.

so

[tex]w=200g[/tex]

for earth the acceleration due to gravity is:  [tex]g=9.81m/s^2[/tex]

thus:

[tex]w=(200kg)(9.81m/s^2)\\w=1962N[/tex]

now we use this value to calculate the mass he can lift on the moon, since for the moon [tex]g=1.62m/s^2[/tex].

we use the same equation, w =mg substituting w = 1962N and [tex]g=1.62m/s^2[/tex]:

[tex]w=mg\\\\1962N=m(1.62m/s^2)\\\\m=\frac{1962N}{1.62m/s^2}\\\\ m=1,211.1kg[/tex]

he can lift 1,211.1 kg.

You can also find the result using the approximate value of the acceleration of gravity on the moon as g/6, where g is the acceleration on earth.

Which structure connects muscles to bone?

Answers

Answer: tendons connect muscles to bones

Explanation:

Two scientists decide to investigate the rate at which objects fall on different planets. They choose to use Earth and Mars as case studies. One scientist stays on Earth and the second goes to Mars. Each of them released a 2kg piece of stone at a height of 15 metres from the surface of the planet at exactly the same time. On which planet will the stone hit the ground first? Why do you think so?

Answers

Answer:

the stones are released from rest at the same time, the stone that is on Earth to have more acceleration must first reach the ground

Explanation:

For this exercise we will use the law of universal attraction on each planet and Newton's second law to calculate the body's acceleration on each planet

          F = ma

          F = G m M / r²

Where G is the universal gravitational constant, m the mass of the body, M the mass of the planet and r the distance

Let's start with the Earth

       G m M / r² = m a

        a = G M / r²

let's look for the distance

    r = [tex]R_{e}[/tex] + h

    a = G M / (R_{e} + h)² = (G M /R_{e}²)  1 /(1 + h /R_{e})² ²

as h << R_{e} we can expand this function

    (1 + h /R_{e})⁻² = 1 -2 h / Re + ...

with h /R_{e} it is very small we can despise it

        a = G M /R_{e}

the amount in parentheses is called the acceleration due to gravity

     g = G M / R_{e}²

     g = 6.67 10⁻¹¹ 5.98 10²⁴ / (6.37 10⁶)²

     g = 9.8 m / s ²

Now let's calculate the acceleration on Mars, let's use index 2 for this planet

     a = G M2 / R_{2}²

     a = 6.67 10⁻¹¹ 6.42 10²³ / (3.37 10⁶)

     a = 3.77 m / s²

Let's analyze these results as the stones are released from rest at the same time, the stone that is on Earth to have more acceleration must first reach the ground

 we can use the equation

           y = v₀ t - ½ to t2

           v₀ = 0

           t = √ (2y / a)

we see that as the acceleration is greater the time decreases

Other Questions
A movie membership costs $10 a month plus an additional $5 for each movie purchased. If you have only budgeted to spend a maximum of $25 this month, how many movies can you purchase? I need help with this problem A sample of diborane gas has a pressure of 345 torr at a temperature of -15c and volume of 3.48L if conditions are changed so that the temperature is 36c and the pressure is 468 torr what will be the volume of the sample Which of the following delivers oxygen to the body? Mark all that apply Arteries Veins Capillaries Hemoglobin During the early 1900s, many African Americans left the cities to farm. true or false What is solfeggio used for Two terms of an arithmetic sequence are a12=70 and a30=124. Write an explicit rule for the nth term. Colil Computer Systems, Inc., manufactures printer circuit cards. All direct materials are added at the inception of the production process. During January, the accounting department noted that there was no beginning inventory. Direct materials of $ 300 comma 000 were used in production during the month. Workminusinminusprocess records revealed that 12 comma 500 card units were started in January, 6 comma 250 card units were complete, and 4 comma 000 card units were spoiled as expected. Ending workminusinminusprocess card units are complete in respect to direct materials costs. Spoilage is not detected until the process is complete. What is the direct material cost assigned to good units completed? A. $ 258 comma 621 B. $ 150 comma 000 C. $ 96 comma 000 D. $ 246 comma 000 Will give brainliest answer What is the volume of the composite figure? Express the answer in terms of pie.1443 mm31687 mm33127 mm3456 mm3 Directional selection only occurs in response to naturally occurring events.Please select the best answer from the choices providedrueFalse There were 632 animals gathered at the river. A herd of 187 elephants and 266 zebras left the river area. How many animals were still at the river? What position did Hitler get in 1933 and how Once a business determines that change needs to occur, what ahould thebusiness create?A. Business operationB. Business analysisC. Business modelD. Business strategy Find (f g)(x).f(x) = 3xg(x) = 5xWrite your answer as a polynomial in simplest form.(fog)(x) = Factor the trinomial:5x2 + 7x + 2 Which word would best fit the connotation of the following sentence?The cold rain splashed down around the old gray house, giving it a ___________ appearance.A. melancholyB. somberC. rattyD. dull Stir-fry is Gabe's favorite food to cook, but it always makes a lot of smoke! Gabe needs to know the volume of his kitchen so he can buy a fan that is the right size. Gabe's kitchen has a floor area of 85 square feet. The height of the ceiling is 8 feet. What is the volume of Gabe's kitchen? Which of the following does not describe the results of the slave trade in the Americas?The slave population in North America grew because many of the slaves were women who had children who also became slaves.Slavery soon became less important in the Americas and most slaves were freed.In North America, life expectancy for slaves was longer than elsewhere in the Americas.Slaves sent to the Caribbean and South America did not live long because of the harsh climate, diseases, and terrible living conditions. hurry timed testThe influential political text The Social Contract was written by