How the speed of particles is affected

  • Thread starter Thread starter Cal124
  • Start date Start date
  • Tags Tags
    Particles Speed
Click For Summary

Homework Help Overview

The discussion revolves around the effects of a moving container of gas on the energy and speed of the gas particles within it. The original poster is exploring concepts related to thermodynamics and kinetic theory, particularly how the motion of the container influences the kinetic energy and behavior of the gas particles.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between the kinetic energy of gas particles and the motion of the container. Questions arise about how the bulk motion of the container affects the internal motion of the particles and their collisions with the container walls.

Discussion Status

Participants are actively engaging with the concepts, questioning assumptions about relative velocities and the implications of kinetic energy in a moving frame. Some have provided clarifications regarding the distinction between bulk motion and internal motion, while others are seeking further understanding of the equations that might relate these concepts.

Contextual Notes

There is an ongoing exploration of the implications of a moving container on gas behavior, including discussions about pressure, temperature, and kinetic energy. Participants are considering the transition from a stationary to a moving state and the statistical nature of gas behavior.

Cal124
Messages
28
Reaction score
0
Apologies if this isn't the right place but I saw a moderators post saying all questions should be posted in this section.
My physics knowledge is at a general A-level standard at the moment, I was curious about something and was just wondering if someone could help me find an answer.

My question: If a container of gas is traveling at a speed, would this affect the energy of the particles ?

I have a brief understanding of some Thermodynamics and I can't seem to find an answer everything I search it talks about the collisions with the surface of the container. I understand the relationship between volume, pressure and temperature with the three gas laws. I could be wrong but temperature is related to the energy of the particles? and the energy is related to the speed of the particles so if the particles (in a container) where traveling at a speed would this affect the speed/energy of the particles?
If I'm not completely wrong, does an equation exist?
I feel like this is a stupid question because I keep thinking about e=mc2 but that would be to work out the energy of the particles right? so I guess my question relates to: does the speed of the container affect the speed of the particles?

Sorry if my question isn't clear, first time on this forum. Thanks to anyone who takes the time to read.
Cal
 
Last edited:
Physics news on Phys.org
Yes, the particles would have more kinetic energy, but you need to distinguish between the kinetic energy of a coordinated motion, i.e. all the particles traveling together, and the random motion of the particles moving with respect to each other. The latter is the 'internal' energy, and its availability to do work is subject to the laws of thermodynamics. It is responsible for pressure on the container. The former exerts no pressure on the container and is entirely available to do work.
Admittedly the boundary can be fuzzy. Wind is a bulk movement on one scale, but on another there are eddies etc.
 
Thanks haruspex,
I have a little confusion over whether the increase in KE would affect the particle collisions?
Thanks for your time
 
Cal124 said:
Thanks haruspex,
I have a little confusion over whether the increase in KE would affect the particle collisions?
Thanks for your time
No. Their relative velocities are not affected by their common bulk velocity.
 
Sorry last question, but even if their bulk velocity doesn't affect the relative. if the container is moving at a speed, when the particles collide with the surface of the container would this not affect the speed?
so would the KE gained not affect the energy needed for a successful collision? apologies if you did answer that,
thanks
 
Cal124 said:
Sorry last question, but even if their bulk velocity doesn't affect the relative. if the container is moving at a speed, when the particles collide with the surface of the container would this not affect the speed?
so would the KE gained not affect the energy needed for a successful collision? apologies if you did answer that,
thanks
Originally you asked about a container of gas traveling at speed. I took that to be in a steady state, i.e. the average speed of the particles equals the average speed of the container. If so, the relative speed of particle to container is the same as if the container were at rest.
Perhaps now you are considering the transition from container at rest to container moving. During that transition, there will be a difference between average particle velocity and container velocity, causing a net pressure on he trailing end of the container. But pretty soon that will bring the average velocity of the particles up to match that of the container.
 
  • Like
Likes   Reactions: 1 person
haruspex said:
Originally you asked about a container of gas traveling at speed. I took that to be in a steady state, i.e. the average speed of the particles equals the average speed of the container. If so, the relative speed of particle to container is the same as if the container were at rest.
Perhaps now you are considering the transition from container at rest to container moving. During that transition, there will be a difference between average particle velocity and container velocity, causing a net pressure on he trailing end of the container. But pretty soon that will bring the average velocity of the particles up to match that of the container.

That's great, thanks, its given me a better understanding. Sorry my question wasn't to clear, I guess I'm trying to understand the relationship between the speed of the container and the particles speed & energy.
Is there an equation to show the relationship? would the SUVAT equations be used?
 
Cal124 said:
That's great, thanks, its given me a better understanding. Sorry my question wasn't to clear, I guess I'm trying to understand the relationship between the speed of the container and the particles speed & energy.
Is there an equation to show the relationship? would the SUVAT equations be used?
SUVAT equations are most easily applied when there's a relatively small number of objects, each rigid. With a vast ensemble, such as in a gas body, you often need to take a more statistical approach. E.g., during acceleration of the container, how to determine the mass centre of the gas body?
 
  • Like
Likes   Reactions: 1 person
haruspex said:
SUVAT equations are most easily applied when there's a relatively small number of objects, each rigid. With a vast ensemble, such as in a gas body, you often need to take a more statistical approach. E.g., during acceleration of the container, how to determine the mass centre of the gas body?

So to see the relationship between the particles and the speed of the container, you could use the following?
3/2 RT (=KE of gas molecules) + 1/2 mv2 (container)
but this doesn't obey,
PV = nRT
or P = T
If there is not a change in pressure, this will = no change in temperature but how can there be an increase in KE but no change in temperature?
I'm not sure if external links are aloud on this site, but is there anyway you can point me in the right direction for information on Kinetic theory of gases with a moving container?
 
  • #10
Cal124 said:
If there is not a change in pressure, this will = no change in temperature but how can there be an increase in KE but no change in temperature?
To an observer outside the moving container, there is an increase in temperature, but in everyday environments it is very small. What is the average speed of an air molecule at NTP? That's the sort of relative speed you need to see the change. Think of an object entering Earth's atmosphere at great speed. To the object, the atmosphere seems extremely hot.
 

Similar threads

  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 2 ·
Replies
2
Views
768
  • · Replies 12 ·
Replies
12
Views
3K
Replies
5
Views
2K
Replies
2
Views
880
Replies
6
Views
2K
Replies
12
Views
2K
  • · Replies 3 ·
Replies
3
Views
678
  • · Replies 5 ·
Replies
5
Views
1K