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Maurinko [17]
3 years ago
9

A train travels 72 kilometers in 1 hours, and then 64 kilometers in 1 hours. What is its average speed?

Physics
1 answer:
garri49 [273]3 years ago
5 0

To find the average of something you must first add everything together and then divide it by the total amount of numbers you added together.

First add 72 and 64 together

72+64=136

Now divide 136 by 2

136/2=68

So the average speed of the train is 68 kilometers

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Ejection of Electrons from Hydrogen by Incident Photons Light of wavelength 80 nm is incident on a sample of hydrogen gas, resul
timofeeve [1]

Answer:

a)   K_{max} = 1.9 eV = 3.04 10⁻¹⁹ J,b ) This means that some electrons are at the first excited level of the hydrogen atom, which is highly likely as the temperature rises.

Explanation:

a) To calculate the maximum kinetic energy of the expelled electrons let's use the relationships of the photoelectric effect

      K_{max}= h f - Φ

Where K is the kinetic energy, h the Planck constant that is worth 6.63 10⁻³⁴ Js, f the frequency and Φ the work function

The speed of light is related to wavelength and frequency

     c = λ f

Let's analyze the work function, it is the energy needed to start an electron from a metal, in this case to start an electron from a hydrogen atom its fundamental energy is needed, so

     Φ= E₀ = 13.6 eV

let's replace and calculate the energy of the incident photon

     E = h c / λ

     E = 6.63 10⁻³⁴ 3 10⁸/80 10⁻⁹

     E = 2,486 10⁻¹⁸ J

Let's reduce to eV

     E = 2,486 10⁻¹⁸ (1 eV / 1.6 10⁻¹⁹)

     E = 15.5 eV

Now we can calculate the kinetic energy

     K_{max}= h c / f - fi

      K_{max} = 15.5 -13.6

     K_{max} = 1.9 eV

b)     Extra energy = 10.2 eV

The total kinetic energy of electrons is

       Total kinetic energy = 1.9 +10.2 = 12.1 eV

For the calculation we are assuming that all the electors are in the hydrogen base state, but for temperatures greater than 0K some electors may be in some excited state, so less energy is needed to tear them out of hydrogen atom.

Let's analyze this possibility

      ΔE = E photon - Total kinetic energy electron

      ΔE = 15.5 - 12.1

      ΔE = 3.4 eV

If we use the Bohr ratio for the hydrogen atom

     E_{n} = 13.606 / n2

     n = √ 13.606 / En

     n = √ (13606 / 3.4)

     n = 2

This means that some electrons are at the first excited level of the hydrogen atom, which is highly likely as the temperature rises.

8 0
3 years ago
What happens when an electron moves from an excited state to the ground state?
Darina [25.2K]
<span>When an electron moves from an excited state to the ground state, "Energy releases"

Hope this helps!</span>
6 0
3 years ago
If you wanted to know the location of a vehicle that ran out of gas after taking a zigzag route through the city, which quantity
Papessa [141]

Explanation:

the vehicles displacement, since displacement deals with position

8 0
3 years ago
A box having a mass of 0.2 kg is dragged across a horizontal floor by
Lyrx [107]

you can check attachment for answer.

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7 0
3 years ago
Clara rushes 30m to a truck then turns and walks back. Total travel is 120s what is her average velocity?
navik [9.2K]

Taking into account the definition of velocity, Clara's average velocity is 0.5 m/s.

<h3>Definition of velocity</h3>

Velocity is a physical magnitude that relates the displacement of an object, the time it takes to make this change in position and direction. So it is considered a vector magnitude.

In other words, the velocity can be defined as the amount of space traveled per unit of time with which a body moves, considering the direction, and can be calculated using the expression:

velocity= distance traveled÷ time

<h3>Average velocity of Clara</h3>

Clara rushes 30 m to a truck then turns and walks back. Total travel is 120s. Then, you know:

  • distance traveled= 30m rushing + 30m walking back= 60 m
  • time= 120 s

Replacing in the definition of velocity:

velocity= 60 m÷ 120 s

Solving:

<u><em>velocity= 0.5 m/s</em></u>

Finally, Clara's average velocity is 0.5 m/s.

Learn more about velocity:

brainly.com/question/4418301

brainly.com/question/24990123

brainly.com/question/14244558

brainly.com/question/25288184

#SPJ1

5 0
2 years ago
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