Is velocity technically a force? Is it drawn as vector in free-body-diagrams?

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Discussion Overview

The discussion centers around the classification of velocity in relation to forces, specifically whether velocity can be considered a force and how it is represented in free-body diagrams. Participants explore the definitions and purposes of different types of diagrams in physics, including free-body diagrams and velocity diagrams.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant questions if velocity is technically a force and whether it should be included in free-body diagrams, citing confusion from a physics expert's statement.
  • Another participant suggests that the diagrams in question may not be free-body diagrams but rather representations of kinematics, emphasizing that free-body diagrams should only include forces.
  • A different viewpoint argues that diagrams can serve various purposes and may mix forces and velocities if clearly distinguished, although caution is advised to avoid ambiguity.
  • One participant asserts that while velocity is not a force, including velocity vectors in diagrams can be helpful for understanding dynamic situations.
  • Another participant reinforces the distinction between force and velocity by referencing their different units, while also acknowledging the utility of including velocity in certain diagrams.

Areas of Agreement / Disagreement

Participants generally agree that velocity is not a force and that free-body diagrams should primarily depict forces. However, there is disagreement regarding the inclusion of velocity in diagrams and the definitions of different types of diagrams, leading to multiple competing views on the topic.

Contextual Notes

There are unresolved issues regarding the definitions of free-body diagrams versus other types of diagrams, as well as the implications of mixing different types of vectors in a single diagram.

Femme_physics
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Is "velocity" technically a force? Is it drawn as vector in free-body-diagrams?

The reaosn I'm asking that is because I was told by a physics expert that you only draw forces in free body diagrams. I also see the velocity (as well as angular velocity) indicated in a lot of free-body-diagrams in my dynamics exercises solution manual.

http://img190.imageshack.us/img190/6449/veloc.jpg Now I'm confused :confused:
 
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Perhaps, these pictures are simply no free-body diagrams but depicting the kinematics of the motion under consideration. In free-body diagrams, you should have indeed only forces!
 


Awww, it's not as strict as all that. :smile:

A diagram needs to serve a purpose.
And it shouldn't be ambiguous.

So you should either draw "only" forces, or "only" velocities.
And still, you can mix them, if it helps explaining how something works.
But make sure then that they are easy to distinguish, for instance by using different colors.
(You like colors, don't you? :biggrin: I like smileys! :cool:)

FBD's are specifically used to analyze the forces acting on the body, which tends to be difficult to do right!
So if you want to make a proper analysis, be careful what else you put in!

The diagrams you have, show "only" velocities, making them unambiguous!
I'm not sure you would call them "free body diagrams" (http://en.wikipedia.org/wiki/Free_body_diagram" ), but you certainly wouldn't call them "force diagrams".
I guess you might call them "velocity diagrams"! :smile:

But really, dictionary English is not my strong suit! :wink:
 
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You can draw whatever you like in a diagram. Just don't add force vectors to velocity vectors, or apples to oranges, or...
 


Force diagram - Velocity diagrams

My brain welcomes your logic! Thanks, ILS :)

And thanks vanhees for feedbacking^^
 


Obviously a "velocity" is not a "force"...just look at the units for each...

But as noted, you can draw what you like to help explain a situation. In static diagrams there is often no ambiguity about direction and motion, say due to gravity; but in dynamic situations it can be helpful to include velocity/momentum direction...also more here:

http://en.wikipedia.org/wiki/Free_body_diagram
 

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