On a free body diagram, is friction always parallel to the surface?
What's an easy way to draw a free body diagram?

Question

On a free body diagram, is friction always parallel to the surface?
What's an easy way to draw a free body diagram?

osprey · Answer

it MAY depend on the coefficient of friction.BUT that said, you can always resolve forces in two perpendicular directions, so there can always be a component parallel to the surface. I THINK ! http://perendis.webs.com

user123 · Answer

this website is crazy @osprey

osprey · Answer

@user123 yup I'd agree with that. I hope I haven't done anything too crazy via my post. If I have, then I apologise. In terms of the q, that seemed to me to be the best answer I could give on the information I saw ...

irishboy123 · Answer

plus, augmenting @osprey's wisdom, a bit of useful mantra....."friction opposes motion".  

so on a surface it will act along the surface, cos typically  there's either sliding or no sliding, depending on the circs.

my 2 cents' (USD or Euro, it doesn't matter anymore!!) worth 

:-)


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easy way to draw a FBD is practise, practise, practise.  until it becomes intuition.  like learning anything that is worth learning...

agent0smith · Answer

Yes, friction is always parallel to a surface (it wouldn't make much sense for it to not be, think about it...)

And practice definitely helps for FBDs. Also just trying to imagine what direction the forces should be acting, using logic/common sense.