An observer is standing next to the tracks, watching a train approach. The train travels at 30 m/s and blows its whistle at 8,000 Hz as it approaches and then passes by the observer without slowing down. Assuming the speed of sound is 340 m/s, how much of a frequency change did the observer hear?

Answer:

[tex]{ \bf{mechanical \: adv = \frac{load}{effort} }}[/tex]

We know

[tex]\boxed{\sf W=Fscos\theta}[/tex]

[tex]\\ \sf\longmapsto W=25(20)cos30°[/tex]

[tex]\\ \sf\longmapsto W=500\times \dfrac{\sqrt{3}}{2}[/tex]

[tex]\\ \sf\longmapsto W=250\sqrt{3}[/tex]

[tex]\\ \sf\longmapsto W=250(1.73)[/tex]

[tex]\\ \sf\longmapsto W\approx 430J[/tex]

Option a) 430 J work done he do after walking 20.0 m.

Work, in physics, is a measure of energy transfer that happens when an object exists moved over a distance by an external force at least part of which exists involved in the direction of the displacement.

Displacement exists as the distance moved in a straight line, in a provided direction, from the starting point. Displacement exists as a vector quantity as it includes size and direction.

An angle stands the figure formed by two rays, named the sides of the angle, sharing a standard endpoint, named the vertex of the angle.

⇒[tex]W=Fcos\theta[/tex]

⇒[tex]W=25(20)cos 30^{0}[/tex]

Then,

⇒[tex]W=50*\sqrt{3} /2[/tex]

⇒[tex]W=250\sqrt{3}[/tex]

Hence,

⇒[tex]W=250(1.73)[/tex]

[tex]W[/tex] approximately 430J.

Hence, Option a) 430 J work done he do after walking 20.0 m.

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Answer:

Acceleration is 0.

Explanation:

Since the girl is running with a uniform velocity, meaning she is moving at a constant rate, she is not accelerating. Acceleration only occurs when the speed of an object increases, decreases, or if there is a change in direction.

Answer:

the gas that escaped from the mixture contained the missing weight

Bear will become extinct due to global warming.

The gases which get easily trapped inside the glasses and increase the temperature of the atmosphere causing the global warming level to increase overall.

Global warming is threatening polar bear habitats and the bears way of life. If global warming continues, predict what will become of the polar bear in the next 10,000 years

Thus, bear will extinct.

Learn more about greenhouse gas.

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Answer:

A) How the size of a tree affect the bird species that prefer to live in it

Explanation:

I took the quiz

Answer:

Direct

Explanation:

Answer:

A concave mirror, or converging mirror, has a reflecting surface that is recessed inward (away from the incident light). Concave mirrors reflect light inward to one focal point. They are used to focus light.

Here are the observations

Sugar:-

Corn syrup:-

Oil:-

Answer:

At point A, the comet has the least kinetic energy because the comet is resting. 3. From point B to point D its orbit's potential energy is decreasing and its kinetic energy is increasing meaning it's moving more and more

Answer:

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Answer:

Amur Leopard, Southeastern Russia, and northern china

Explanation:

Answer:

Amur Leopard    China/Russia

Hawks bill Turtle   live in Oceans

Answer:

The momentum makes it worse.

Explanation:

The momentum of vehicles running at faster speeds is very high and causes a lot of damage to the vehicles.

1:-

[tex]\\ \sf\longmapsto cos\Theta=\dfrac{B}{H}[/tex]

[tex]\\ \sf\longmapsto cos\Theta=\dfrac{4}{5}[/tex]

2:-

[tex]\\ \sf\longmapsto tan\Theta=\dfrac{P}{B}[/tex]

[tex]\\ \sf\longmapsto Tan\Theta=\dfrac{3}{4}[/tex]

Key Notes:-

Answer:

Cos A = 4/5

Tan A = 3/4

Explanation:

Cos A = Adjacent/Hypotenuse = 4/5

Tan A = Opposite/Adjacent = 3/4

Answer:

This type of a behavior is known as oscillation, a periodic movement between two points. ... Amplitude: The distance from the center of motion to either extreme. Period: The amount of time it takes for one complete cycle of motion.

Explanation:

Amplitude (a):- The maximum displacement of particle from its mean position on either side is called amplitude.  

Periodic time:- The time taken by a wave to complete one oscillation is called periodic time.

Answer:

D. has no overall force acting on it.

Explanation:

Why?

Because in a straight line at the constant speed means the car moving in the same velocity, which is not acceleration neither deceleration, and it cannot be on a downhill slope. So the correct answer is

Answer:

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Answer:

The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to other forces of nature.It applies to the cosmological and astrophysical realm, including astronomy.

The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton. It introduced concepts including spacetime as a unified entity of space and time, relativity of simultaneity, kinematic and gravitational time dilation, and length contraction. In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in the nuclear age. With relativity, cosmology and astrophysics predicted extraordinary astronomical phenomena such as neutron stars, black holes, and gravitational waves

Answer:

Three

Explanation:

I hope this helps:)

Answer:

The elements are grouped into the different substances by color. As you can see, Lithium, Beryllium, Sodium, Magnesium, Aluminum, Potassium, and Calcium are metals out of the first 20 elements.

Hydrogen, Helium, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Phosphorus, Sulfur, Chlorine, and Argon, are non-metals within the first 20 elements.

Boron and Silicon count as Metalloids in the Periodic Table (properties of both metals and non-metals)

reference- socatric q and a

Explanation:

Answer:

(11-13) - Metals

(14) - Metalloid

(15-18) - Non- metals

(19-20) - Metals

Explanation:

The elements from 11 to 13 are metals. They are Sodium(Na), Magnesium(Mg) and Aluminum(Al) respectively.

The element 14 is a metalloid. It’s Silicon(Si).

The elements from 15 to 18 are non metals. The 18th element is a noble gas known as Argon(Ar).

The elements from 15 to 17 are Phosphorus(P), Sulphur(S) and Chlorine(Cl).

The elements from 19 to 20 are metals. They are Potassium(K) and Calcium(Ca).

Answer:

Explanation:

As,

In Option,

A:

There are two same positive ions so they will move away from each other.

B:

There is one negative and positive ion so they will move towards each other.

C:

Again there is one negative and positive ion so they will move towards each other.

D:

Here, there is neutral ions so they will not move and its the correct option.

Answer:

they were in the sun for long

Answer:

Q. 1. Newton's Law of gravitation states that all bodies in the universe exerts a force of attraction on all other bodies in the universe with a proportional force to both the product of the masses of the bodies and inversely proportional to the square of the distance between their centers

Mathematically, we have;

[tex]F = G \times \dfrac{m_1 \times m_2}{R^2}[/tex]

Where;

m₁, and m₂ are the masses of the bodies

R = The distance between their centers

G = The gravitational constant = 6.6743 × 10⁻¹¹ N·m²/kg²

The gravitational constant, G, is the Newton's law of gravitation's constant of proportionality between the force of attraction that exist two bodies and the product of their masses divided by the square of the distance between their centers

Q. 2. Newton's law of gravitation in vector form is presented as follows;

[tex]\underset{F_{12}}{\rightarrow} = -G \times \dfrac{m_1 \times m_2}{R_{21}^2} \cdot \hat R_{12}[/tex]

The above equation gives the gravitational force of attraction of body 1 on body 2, with the negative sign and unit vector indicating that the force of of gravity is towards body 1

The force of gravity of body 2 on 1 is presented as follows;

[tex]\underset{F_{12}}{\rightarrow} = -G \times \dfrac{m_1 \times m_2}{R_{12}^2} \cdot \hat R_{21}[/tex]

The gravitational force of attraction of body 2 on body 1 is therefore, equal in magnitude and opposite in direction of the gravitational force of body 1 on body 2 (towards body 2)

[tex]-\underset{F_{12}}{\rightarrow} = G \times \dfrac{m_1 \times m_2}{R_{21}^2} \cdot \hat R_{12} = G \times \dfrac{m_1 \times m_2}{R_{21}^2} \cdot -(\hat R_{21}) = -G \times \dfrac{m_1 \times m_2}{R_{21}^2} \cdot \hat R_{21}[/tex]

[tex]-\underset{F_{12}}{\rightarrow} = -G \times \dfrac{m_1 \times m_2}{R_{21}^2} \cdot \hat R_{21} = \underset{F_{21}}{\rightarrow}[/tex]

[tex]-\underset{F_{12}}{\rightarrow} = \underset{F_{21}}{\rightarrow}[/tex]

Explanation:

Answer:

X = 24.135 kilometres

Explanation:

Given the following data;

Distance = 15 miles

To convert the value in miles to kilometers;

Conversion:

1 mile = 1.609 kilometres

15 miles = X kilometres

Cross-multiplying, we have;

X = 1.609 * 15

X = 24.135 kilometres

Answer:

Efficiency of a machine is defined as the ratio of output work to input work in a machine . It is expressed in percentage and denoted by

η ( eta).

If A = i - j + k, then the magnitude of A is

||A|| = √(1² + (-1)² + 1²) = √3

Then the unit vector in the direction of A is 1/||A|| multiplied by A :

u = A/||A|| = (i - j + k)/√3

(choice D)

Answer:

increase in mass of body