A train moving with a speed of 20.9 m/s sounds a 103 Hz horn. What frequency is heard by an observer standing near the tracks as the train approaches

Answers

Answer 1

Answer:

observed frequency =  109.68 Hz

Explanation:

given data

speed u = 20.9 m/s

frequency f = 103 Hz

solution

we consider here speed of sound (v)  is 343 m/s

so observed frequency is express as

observed frequency = f × [tex]\frac{v}{v-u}[/tex]     ...............1

put here value and we get

observed frequency =  103 × \frac{343}{343-20.9}

observed frequency =  109.68 Hz


Related Questions

calculate the net force

250N left force and right force is 150N​

Answers

Answer

100N on the left force

Explanation:

You have to subtract 250 - 100 and the reamaining would be 100 and that 100 would go to the left force since it was the higher number

Which of the following is the cause of an acceleration?

Answers

[tex]{\tt{\red{\underline{\underline{\huge{Answer:}}}}}}[/tex]

[tex]\longrightarrow[/tex] The rate of change of velocity per unit time is called acceleration.

[tex]\longrightarrow[/tex] Its SI unit is m/s².

[tex]\huge\boxed{\fcolorbox{blue}{red}{Thank you}} [/tex]

we have that from the Question"Which of the following is the cause of an acceleration?" it can be said that  

Acceleration cause bodies to move at an increasing rate after which a velocity or speed is maintained Force is a main cause of Acceleration andacceleration is seen at a change in velocity

From the Question we are told

Which of the following is the cause of an acceleration?

Generally the equation for acceleration is mathematically given as

[tex]a=\frac{F}{m}\\\\or\\\\a=\frac{u-v}{dt}\\\\[/tex]

Therefore

Acceleration cause bodies to move at an increasing rate after with a velocity or speed is maintained Force is a main cause of Acceleration andacceleration is seen at a change in velocity

So in the selection of the option consider these points of acceleration

Acceleration cause bodies to move at an increasing rate after which a velocity or speed is maintained Force is a main cause of Acceleration andacceleration is seen at a change in velocity

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calculate for potential energy

Answers

Answer:

The formula for potential energy depends on the force acting on the two objects. For the gravitational force the formula is P.E. = mgh, where m is the mass in kilograms, g is the acceleration due to gravity (9.8 m / s2 at the surface of the earth) and h is the height in meters

which of the following is true? for this graph.

a. the object increase its velocity.
b. the object decrease its velocity.
c. the objects velocity stays unchanged.
d. the object stays at rest.
e. more information is required.​

Answers

Answer:

b.  The objects velocity is decreasing.

Explanation:

I know this because if you read a graph left to right it will tell u whether it is increasing or decreasing.

PLEASE HELP :(
I WILL GIVE EXTRA POINTS


1. When is the kinetic energy of an electron transformed into potential energy?

when it interacts with other electrons, decreasing its speed

when it interacts with neutrons without changing its speed

when it interacts with neutrons , increasing its speed

when it interacts with other electrons without changing its speed

2. Atoms bond to form molecules. Which structures or regions of the atoms interact in bonds ?

electric fields of particles with positive charge

electric fields of particles with no charge

electric fields of particles with negative charge

electric fields of particles with opposite charges

3. If two electrons that are apart get pushed toward each other, how does the repulsion between them change?

Initial repulsion is low and decreases as they approach .

Initial repulsion is high and decreases as they approach .

Initial repulsion is high and increases as they approach .

Initial repulsion is low and increases as they approach .

4. A positive charge of 5.0x10 ^ -5 C °is 0.040 m from a second positive charge of 2.0x10 ^ -6 C Calculate the force between the charges.

5.6x10^2 N

5.6x10^2 N

1.4X10^-2 N

2.3X10^1 N

Answers

(a) When the kinetic energy of an electron is transformed into potential energy is when it interacts with other electrons, decreasing its speed.

(b)  The region of atoms that interact in bonds is electric fields of particles with negative charge.

(c) Initial repulsion is low and increases as they approach.

(d) The force between the charges is 562.5 N.

Kinetic theory of matter

This theory states that, the collision of particles (electrons) of matter is perfectly elastic. This implies that as the particles (electrons) collides with one another, kinetic energy is transferred from one electron to another.

ΔK.E = ΔP.E

Change in kinetic energy is equal to change in potential energy of the electrons.

Thus, when the kinetic energy of an electron is transformed into potential energy is when it interacts with other electrons, decreasing its speed. Decrease in speed implies decrease in kinetic energy and increase in potential energy.

Chemical bonds of molecules

Chemical bond is formed from the transfer or sharing of electrons between atoms. (electrons between atoms implies negative charge to negative charge)

Thus, the region of atoms that interact in bonds is electric fields of particles with negative charge.

Coulomb's law

This law states that the force of attraction or repulsion between two charges is directly proportional to the product of the charges and inversely proportional to the distance between the charges.

[tex]F = \frac{kq_1q_2}{r^2}[/tex]

When the distance between the electrons are large, the repulsive force is low and the distance is small, the repulsive force is high.

Force between the charges

The force between the charges is determined by applying Coulomb's law,

[tex]F = \frac{kq_1q_2}{r^2} \\\\F = \frac{9\times 10^9\times (5 \times 10^{-5}) \times (2\times 10^{-6})}{0.04^2} \\\\F = 562.5 \ N[/tex]

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Match the scienntist with their accomplishment / discoveries

Answers

Answer:

newton - motion, gravity

kepler - orbital paths

brahe - the sun goes around the earth

Explanation:

im not sure about brahe but its the only one that makes sense

If the x-component of vector A in the figure below is 3cm and the y component of A is 4cm, then what is the vector quantity of A?

Question 9 options:

25 cm - 37 degrees


7 cm - 37 degrees


7 cm - 53 degrees


5 cm - 53 degrees

Answers

Answer:

5 cm - 53 degrees

Explanation:

[tex] \sqrt{ {4}^{2} + {3}^{2} } = 5cm[/tex]

[tex] \tan ^{ - 1} (4 \div 3) [/tex] = 53°

Which of the following is correct? *
PLEASE HELP MEEEE
1 cm = 100 m
1 mm = 100 cm
100 mm = 1 cm
1 m = 100 cm

Answers

Answer:

The last one

1m = 100 cm

Explanation:

If you do not trust me look it up

a hiker walks westward 2 meters and then eastward 7 meters. for this motion the distance moved is?​

Answers

Answer:

d = 9 [m]

Explanation:

This is a problem where we must be clear about the concept of distance, which tells us that it is a measure of the space traveled on a trajectory.

Therefore:

d = 2 + 7

d = 9 [m]

The directions are not taken into account, as it is the sum of the displacements traveled, regardless of their directions.

If you take a trip from Earth (g = -9.8 m/s2) to Pluto (g = -0.6 m/s2) what would happen to your mass and weight?
A. your mass would stay the same and your weight would stay the same
B. your mass would decrease and your weight would decrease
C. your mass would decrease and your weight would stay the same
D. your mass would stay the same and your weight would decrease

Answers

The D is the correct answer your mass does not change your weight decrease s

A 96 kg man lying on a surface of negligible friction shoves a 75 g stone away from himself, giving it a speed of 7.2 m/s. What speed does the man acquire as a result?

Answers

Answer:

7.21m/s

Explanation:

Using the law of conservation of momentum expressed as;

m1u1 + m2u2 = (m1+m2)v

m1 and m2 are the mass of the man and the stone respectively

u1 and u2 are their respective initial velocities

v is their final common velocity

Given

m1 = 96kg

m2 = 75g = 0.075kg

u1 = ?

u2 = 0m/s (initial speed of the stone)

v = 7.2m/s

Substitute into the firmula and get u1

96u1 + 0.075(0) = (96 + 0.075)(7.2)

96u1 = 96.075(7.2)

u1 = 691.74/96

u1 = 7.21m/s

Hence the man acquired a speed of 7.21m/s

A horse travels 1200 meters to the right in 60 seconds. What was its velocity?

a. 72,000 m/s
b. 20 m/s
c. 0.05 m/s
d. 1260 m/s​

Answers

Answer:

a

Explanation:

If its not right choose D

true or false The most extreme tides occur during a new
moon and full moon.

Answers

Answer:

true

Explanation:

Help me please..

Suppose a car is moving in a straight line and steadily increases its
speed. It goes from 0 miles/hour to 15 miles/hour the first second and 15
miles/hour to 30 miles/hour the next second. What is the acceleration?

A)10 miles/hour/second

B) 15 miles/hour/second

C) 20 miles/hour/second

D)30 miles/hour/second

Answers

it’s B, 15 miles per hour

The speed of revolution of particle going around a circlr is doubled and its angular speed is havled. What happen to the centripetal acceleration?
a) unchanged
b) doubles
c) halves
d) becomes four times​

Answers

Answer: The correct answer is C

Explanation:

which property of an object is not changed by a force​

Answers

Cannot changed by force hope this help

When you look at yourself in a convex mirror, you appear to be ¼ your actual size. If you are standing 1.0 m in front of the mirror, what is the mirror’s focal length and radius of curvature. (Be sure to first sketch the situation).

Answers

Answer:

The focal length is   [tex]f = -0.2 \ m[/tex]

The radius of curvature is [tex]R = -0.4 \ m[/tex]

Explanation:

From the question we are told that

       The magnification of the mirror is  [tex]m = \frac{1}{2}[/tex]

       The distance of the person from the mirror(the object distance ) is  [tex]u = - 1.0 \ m[/tex]

        The negative sign shows that it is been placed in front of the mirror

         

Generally the magnification of the mirror is mathematically represented as

       [tex]m = \frac{v}{u}[/tex]

=>   [tex]\frac{1}{4} = \frac{v}{-u}[/tex]

=>   [tex]v = \frac{- 1}{4}[/tex]

Generally from the lens equation we have that

        [tex]\frac{1}{f} = \frac{1}{u} + \frac{1}{v}[/tex]

=>     [tex]\frac{1}{f} = \frac{1}{-1 } + \frac{1}{-\frac{1}{4} }[/tex]

=>     [tex]f = -0.2 \ m[/tex]

Generally the radius of curvature is  mathematically represented as

         [tex]R = 2 * f[/tex]

=>      [tex]R = 2 * - 0.2[/tex]

=>      [tex]R = -0.4 \ m[/tex]

why is lighting visible before thunder is heard

Answers

Answer: Lightning is mostly light and electricity, this light that is hitting is going at a rate of 299,792.458 km per second (or 186,282 miles per second) this is so much compared to sound which only travels at about 761 mph (or approximately 332 meters per second). Fun fact: The lightening you are seeing is that coming back to the cloud because the process happens so fast.

Explanation:

Answer:

Light is faster than sound.

Explanation:

Help me please

What is the shape of the velocity vs time graph for an object going at constant speed?

A- A curve that rises gradually to the right

B- A curve that decreases gradually to the right

C- A straight line that rises gradually to the right

D- A strait line that decreases gradually to the right

E- A straight line that is level and neither increases or decreases going to the right

Answers

Answer: a or b can u pls give me brainlest

Explanation:A straight line is a curve with constant slope. Since slope is acceleration on a velocity-time graph, each of the objects represented on this graph is moving with a constant acceleration.

A piston contains oxygen at 280 k occupying a volume of 0.25m3. The cylinder is compressed adiabatically to 0.14 m3, find the increase in temperature of the gas.

Answers

dhvxdryvbjjolbcsdfunnlpifsaf

Drag each label to the correct location on the chart.
Sort the items based on whether they are simple machines or compound machines.

Answers

Answer:

whatttttttttttttttttttttttttttt are the items we have to classify into simple machines and compound machine

two spheres A and B are projected off the edge of a 1.0 m high table with the same horizontal velocity . sphere A has a mass of 20.g and sphere B has a mass of 10.g.
     If both spheres leave the edge of the table at the same instant, sphere A will land
a.    at some time after sphere B.
b.    at the same time as sphere B.
c.    at some time before sphere B.
d.    There is not enough information to decide.

__ 6.    If both spheres leave the edge of the table at the same instant, sphere A hits the floor at the spot marked X.  Sphere B will hit the floor
a.    at some point between the edge of the table and X.
b.    at some point past X.
c.    at the same distance from the table as X.
d.    there is not enough information to ​

Answers

Answer:

A lands first and then for the second question i think there is not enough information

Explanation:

What is the flash of light commonly associated with thunderstorms called?
a. Downdrafts
b. Updrafts
c. Return stroke
d. Thunder
e. Step-leader

Answers

Answer:

C.

Explanation:

Return stroke

A return stroke is termed to be the most visible part of a lightning, which in itself is accompanied by a thunderstorm. Lightning causes thunder, which like I said, is a sound from the shock wave that develops like gases in the areas of the discharge. While experiencing a sudden increase in its pressure. Lightning occurs naturally and is electrically charged.

it is easier to climb up a slanted slope than a vertical slope

Answers

Answer:

Yes, it is easier to climb a slanted slope than a vertical or more steep slope.

Explanation:

On a vertical slope, you are climbing higher instead of farther so on each step gravity weighs you down much more than on a gentle slope

Yes it is easier to clime a gentle slope than a vertical or more steep slope. This is because gravity is always pulling objects down so when you climb upward gravity weighs you down, you have to use effort to move yourself in the opposite direction that gravity is pulling you that is why it is harder to climb up a slope. When you climb a gentle slope you still are using energy but it takes longer to reach the same height on a gentle slope versus a vertical slope. On a vertical slope you are climbing higher instead of farther so on each step gravity weighs you down much more than on a gentle slope. When climbing a gentle slope you don't rise as rapidly so gravity doesn't take as much of a toll on you and you have a chance to recover.

Suppose one night the radius of the earth doubled but its mass stayed the same. What would be an approximate new value for the free-fall acceleration at the surface of the earth?

Answers

Answer:

g' = g/4

Explanation:

The value of the free-fall acceleration at the surface of the earth, can be obtained applying Newton's 2nd law, assuming that the only force acting on an object at the surface of the earth, is the one produced by the mass of the Earth, i.e. gravity.This force can be expressed according  the Newton's Universal Law of Gravitation , as follows:

       [tex]F_{g} = G*\frac{m_{x} *m_{E} }{r_{E}^{2} } (1)[/tex]

From Newton's 2nd Law, we have:[tex]F = m* a (2)[/tex]Since the left sides in (1) and (2) are equal each other, both right sides must be equal each other also.Simplifying the mass m, we can write the acceleration a in (2) as the acceleration due to gravity, g, as follows:

       [tex]g = G*\frac{m_{E} }{r_{E}^{2} } (3)[/tex]

Since G is an universal constant, and the mass mE remains constant, if we double the radius of  the Earth, the new value for the acceleration due to gravity (let's call it g'), is as follows:

        [tex]g' = G*\frac{m_{E} }{(2r_{E})^{2} } =G*\frac{m_{E} }{4*r_{E}^{2} } = g*\frac{1}{4} =\frac{g}{4} (4)[/tex]

what would the net force be on the box in the problems shown below.( both force and direction).​

Answers

Answer:

4

Explanation:

The net force on the box a will be 20 N to the left and that on box b is 6 N downwards. The net force on box  c is 90 N to the left and that on box d is zero.

What is net force?

Force is an external agent acting on a body to change its motion or to deform it. The net force acting on a body depends on all the the forces with their magnitudes and directions.

If two same or different forces acts from the same direction they will add up and net force will be their sum. If they acts from the different directions, they will cancel each other in magnitudes.

In box a, the equal forces of 20 N opposes from each direction cancel and the net force will be 20 N to the left. I box b the 15 N cancel each other. Where the 4N and 2 N add up to have net force of 6 N downwards.

In box c, 10 N from opposite direction cancels and the 60 N and 30 N to the left add ups to have the net force of 90 N to the left. On box d, 5 N from opposite directions cancels as 12 N. Hence, net force is zero.

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If your heart is beating at 76.0 beats per minute, what is the frequency of your heart's oscillations in hertz?A) 3.98 HzB) 4560 HzC) 2.54 HzD) 1450 HzE) 1.27 Hz

Answers

Answer:

E) 1.27 Hz

Explanation:

If the heart beats 76 times in a minute, this means that the time needed for a single beat (the period of the oscillation), is just 1/76 of a minute, as follows:

       [tex]T = \frac{1}{76} min = 0.013 min = 0.79 sec. (1)[/tex]

The frequency of the oscillation, by definition, is just the inverse of the period T, as follows:

      [tex]f = \frac{1}{T} = \frac{1}{.79sec} = 1.27 Hz (2)[/tex]

The right answer is the E).

what two charactoristic are needed to describe a force

Answers

Answer:

An applied force, A resistive force

Explanation:

An applied force is an interaction of one object on another that causes the second object to change its velocity.

A resistive force passively resists motion and works in a direction opposite to that motion.

A dog can provide sufficient power to pull a sled with a 60 N force at a steady 2.0 m/s. Suppose the dog is hitched to a different sled that requires 120 N to move at a constant speed. How fast can the dog pull this second sled?

Answers

Answer:

v = 1.0 m/s

Explanation:

Applying the definition of power (rate of change of energy with respect to time), and the definition of average speed, we can say that the power is the product of the net force applied, times the speed achieved by the force on the mass of the object, as follows:P = F* vIn this case, this power can be written as follows:P = 60 N * 2.0 m/s = 120 J/s = 120 WIf the power remains constant, but now it is required a force of 120 N to move the sled at a constant speed, it is clear that the maximum speed possible will be 1.0 m/s, due to 120 N* 1.0 m/s = 120 W, which is the maximum power available.

How would the mass and weight of an object on the Moon compare to the mass and weight of the same object on Earth? * Mass and weight would both be less on the Moon. Mass would be the same but its weight would be less on the Moon. Mass would be less on the Moon and its weight would be the same. Mass and weight would both be the same on the Moon.​

Answers

Answer:

B. Mass would be the same but its weight would be less on the Moon.

Explanation:

The mass of a body can be expressed as the quantity of matter it contains. While the weight of a body is the extent of the gravitational force impressed on the body by a massive body.

Thus, the mass of a body is constant either on the Earth or on the Moon. But the weight would be less on the Moon because the gravitational force on the Moon is far less than that on the Earth. Therefore the weight would be less on the Moon.

The appropriate option is B.

The mass will remain same on both moon and Earth, but weight will be lesser on Moon than Earth. Hence, option (B) is correct.

The prime focus to solve this problem is the mass and weight of an object. The mass of a body can be expressed as the quantity of matter it contains. While the weight of a body is the extent of the gravitational force impressed on the body by a massive body.

So, the mass of a body is constant either on the Earth or on the Moon. But the weight of an object will depend on the mass and the gravitational acceleration.

W = mg

Here, W is weight, m is mass and g is gravitational acceleration.

Weight would be less on the Moon because the gravitational force on the Moon is far less (due to lower value of g) than that on the Earth. Therefore the weight would be less on the Moon.

Thus, we can conclude that the mass will remain same on both moon and Earth, but weight will be lesser on Moon than Earth. Hence, option (B) is correct.

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