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

[Femme_physics]

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

 

[vanhees71]

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!

 

[I like Serena]

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

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? I like smileys! )

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"!

But really, dictionary English is not my strong suit!

 

[jtbell]

You can draw whatever you like in a diagram. Just don't add force vectors to velocity vectors, or apples to oranges, or...

 

[Femme_physics]

Force diagram - Velocity diagrams

My brain welcomes your logic! Thanks, ILS :)

And thanks vanhees for feedbacking^^

 

[Naty1]

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