How the speed of particles is affected

In summary, the conversation discusses the relationship between the speed of a container of gas and the energy of the gas particles. The summary explains that the particles will have more kinetic energy due to their coordinated motion, but this does not affect the random motion responsible for pressure on the container. The summary also addresses the question of whether the speed of the container affects the speed of particle collisions, and explains that during the transition from a stationary to moving container, there may be a difference in average velocities causing a net pressure on the container. The summary concludes by noting that for a large ensemble of gas particles, a statistical approach may be needed to understand the relationship between particle speed and container speed.
  • #1
Cal124
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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
 
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  • #2
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.
 
  • #3
Thanks haruspex,
I have a little confusion over whether the increase in KE would affect the particle collisions?
Thanks for your time
 
  • #4
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.
 
  • #5
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
 
  • #6
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.
 
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  • #7
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?
 
  • #8
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?
 
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  • #9
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.
 

FAQ: How the speed of particles is affected

1. How does temperature affect the speed of particles?

Temperature is directly proportional to the speed of particles. As the temperature increases, the particles gain kinetic energy and move faster. This is because the increased temperature causes the particles to vibrate and collide more frequently, increasing their speed.

2. Does the size of particles affect their speed?

Yes, the size of particles does affect their speed. Smaller particles tend to have higher speeds than larger particles. This is because smaller particles have less surface area, allowing them to move more freely and collide less frequently with other particles.

3. How do external forces impact the speed of particles?

External forces, such as gravity or electromagnetic fields, can affect the speed of particles. These forces can either increase or decrease the speed of particles, depending on their direction and strength. For example, gravity can cause particles to accelerate and increase in speed.

4. Can the state of matter affect the speed of particles?

Yes, the state of matter can affect the speed of particles. In solids, particles are tightly packed and have less room to move, so their speeds are relatively low. In liquids, particles have more room to move and are constantly colliding, resulting in higher speeds. In gases, particles have the most room to move and are constantly colliding, resulting in the highest speeds among the three states of matter.

5. How does the density of a substance affect the speed of particles?

The density of a substance does not directly affect the speed of particles. However, it can indirectly impact speed by affecting the temperature and pressure of the substance. For example, in a more dense substance, particles are closer together and can collide more frequently, resulting in higher temperatures and faster speeds.

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