Random Translational Motion vs. Uniform in Fluids Recap

[SaintJude]

Recap : Is this the basic gist of Random vs. Uniform Translation Motion? Anything else I'm missing?

RTM Responsible for: (associated w/ collision within a fluid)
fluid pressure at rest
average Kinetic energy
& temperatures, as it relates to changes in KE (ave)

Uniform translational motion:
It's motion of the fluid as a whole ---It's related to fluid velocity

Energy of 2 types of motion can be converted back & forth. So when uniform translation motion increases (through increased fluid velocity, for instance) then random translational motion decreases at that point in a fluid. Bernoulli's equation relates this energy conversion of these 2 types motions: greater fluid velocity, decrease in pressure

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[ljc]

You've got it. The only other thing I might add in (though this isn't nearly as important), is that temperature theoretically goes down as uniform translational motion goes up, for the same reason pressure goes down.

 

[chiddler]

You've got it. The only other thing I might add in (though this isn't nearly as important), is that temperature theoretically goes down as uniform translational motion goes up, for the same reason pressure goes down.

that's a good point i never thought of. it's because random translational motion decreases, right?

 

[ljc]

that's a good point i never thought of. it's because random translational motion decreases, right?

Yep. And temperature is a measure of random motion. Same reason that a bucket of water doesn't heat up when you drop it off a building.

 

[MedGrl@2022]

Yep. And temperature is a measure of random motion. Same reason that a bucket of water doesn't heat up when you drop it off a building.

Would it be accurate to say that random translational motion of a fluid "creates" temperature as it is the Kinetic Energy of random motion which is responsible for temperature increases right? So as random translational motion increases so does temperature and visa versa?

Please let me know if I am on the right page and I am stating it and understanding it correctly.

Thank you!

 

[milski]

Would it be accurate to say that random translational motion of a fluid "creates" temperature as it is the Kinetic Energy of random motion which is responsible for temperature increases right? So as random translational motion increases so does temperature and visa versa?

Please let me know if I am on the right page and I am stating it and understanding it correctly.

Thank you!

You have the right idea but I would not necessary use the word 'create' there. It's a bit like saying that movement creates speed - not very formal but sort of ok if you want to think about concepts. Temperature is a measurement of thermal energy, which does include the kinetic energy from random motion. Your logic about increasing KE being tied to increasing temperature is technically better phrased.

 

[SKation]

Hey guys,

this may be a dumb question but is uniform translational movement, the movement of articles in the same direction with no colliding?

Thanks!

 

[Czarcasm]

Hey guys,

this may be a dumb question but is uniform translational movement, the movement of articles in the same direction with no colliding?

Thanks!

I always took translational as meaning from point to point (in comparison to rotational kinematics for example, which ossicilates through the same point, although I suppose that doesn't necessarily hold true all the time). EK defines translational energy for example as: "the movement of the center of mass of a molecule." Rotational energy as "molecular movement where the spatial orientation of the body changes" and Vibrational energy, "created by the atoms vibrating within a molecule."

 

[NextStepTutor_1]

Hey @SKation,

In response to your question, uniform transnational motion is simply motion that is constant in velocity (magnitude and direction). Thus, in this case, when we apply it to fluid motion, we can see that the uniform transnational motion of water molecules causes the fluid to flow in the same direction and speed to cause motion with a lower viscosity and loss of energy.