Cant understand those lines in a text about solid state physics

In summary, the conversation discusses calculating the heat energy of a gas molecule, with variables such as n (number of molecules per volume), v_th (average speed of gas molecule), and L (distance traveled in a certain time). The group also discusses how gas molecules constantly change direction and the average of 6 possible directions is taken. The conversation also touches on a formula for calculating the density and material energy of a gas, with a question about why the variable n is added in the solution.
  • #1
nhrock3
415
0
"we want to calculate the heat enrgy of a gas molecule
n - is the number of molecules per volume
v_th - is the average speed of gas molecule
L - is the distance which travels one molecule in a certain time

we have six directions for which they travel
+-x +-y +-z

so in each time n/6 of the molecules travel in every one of those 6 dircetion."


i can't see how?
we have n molecules why they divided evenly
it could be the in the +z direction move 5/6n of the molecules

??
 
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  • #2
Gas molecules are energetic and bounces off of walls and gazillions of other gas molecules. As a result they constantly change direction. That's why it's impractical to assign one specific direction because in the next moment a gas molecule will bounce off something and fly in the opposite direction. That's why the average of 6 possible directions is taken.
 
  • #3
thanks :)
next question about missundertood text:(question 2)
"the total amount of molecules which hit an area unit in a certain time
equals 1/6 of the number of molecules which present in the rectangular box
the area of its base is L=V_th*1
so
we have 1/6 * n *L=(n*V_th)/6
"
a bout this
L=V_th*1
V_th is the speed .sped times 1 cannot be area?

how they got
1/6 * n *L*1=(n*V_th)/6
?
n is the number of molecules per volume ,L is the distance which travels in some time
so i can't understand what is the result of multiplying dencity by distance
its undefined.

n*V_th is speed time density another undefined unit
??
 
Last edited:
  • #4
(question 3)
formula question:"
calculate the density n and its the material energy of a gas which is contained in presure 5 and termperature 325k"

i am not asking you to solve this homw work question
my question is about the formula
i know that
[tex]
\frac{mv_{th}^2}{2}=\frac{3}{2}kT[/tex]
the left side represent the total energy
or
[tex]
E=\frac{3}{2}kT[/tex]
so i used this formula
but in the solution they use
[tex]
E=n\frac{3}{2}kT[/tex]
why they added the n?
 
  • #5
nhrock3 said:
(question 3)
formula question:"
calculate the density n and its the material energy of a gas which is contained in presure 5 and termperature 325k"

i am not asking you to solve this homw work question
my question is about the formula
i know that
[tex]
\frac{mv_{th}^2}{2}=\frac{3}{2}kT[/tex]
the left side represent the total energy
or
[tex]
E=\frac{3}{2}kT[/tex]
so i used this formula
but in the solution they use
[tex]
E=n\frac{3}{2}kT[/tex]
why they added the n?

I'm not sure this is helpful, but if you are wanting to determine the density of an ideal gas, n, wouldn't you want to use p=nkT where p is the pressure, T is the temperature, and k is Boltzmann's constant?
 
  • #6
i need to calculate the energy too
my dilema is about the formula they used its not like the formal formulaa
 

1. Why is understanding solid state physics important?

Understanding solid state physics is important because it helps us to better understand the properties and behavior of materials at the atomic and molecular level. This knowledge is essential for developing new technologies and materials that have a wide range of applications in fields such as electronics, energy, and medicine.

2. What are the main principles of solid state physics?

The main principles of solid state physics include crystal structure, electronic band structure, and lattice vibrations. These principles help us to understand how atoms are arranged in a solid, how electrons behave in different materials, and how energy is transferred through a solid.

3. What are some common techniques used in solid state physics research?

Some common techniques used in solid state physics research include X-ray diffraction, electron microscopy, and spectroscopy. These techniques allow scientists to study the structure, composition, and properties of materials at the atomic and molecular level.

4. How does solid state physics relate to other branches of physics?

Solid state physics is closely related to other branches of physics such as condensed matter physics, materials science, and quantum mechanics. It provides a fundamental understanding of the behavior of matter at the atomic and molecular level, which is essential for many other areas of physics.

5. What are some real-world applications of solid state physics?

Solid state physics has many real-world applications, including the development of electronic devices such as transistors, solar cells, and computer chips. It is also used in the production of new materials for energy storage, medical devices, and advanced sensors. Additionally, solid state physics research has led to advancements in fields such as nanotechnology, quantum computing, and renewable energy.

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