Coefficient of Friction (Need help on this asap)

[Gurpy]

Hey,

So I have a lab due tomorrow and we just learned about coefficient of friction. I need to get this lab done and I have no idea how to do calculate it. Should be pretty straight forward though?

I just need to ask one question (please explain how to do it also) and i'll be able to figure out the rest from that. Thanks

Determine the coefficient of sliding friction between the larger area side of the block on the lab bench.

Weight of block = 1.75 N/1.62 G
Force to pull block = 0.25 N

Thanks

-Gurpy

[V6-BoI]

I'll give it a shot not too sure if I'm right, haven't done physics in like a few years.

Okay so if you draw a free body diagram you have the force of gravity acting on the block pointing downwards (Fg which is the weight of hte block 1.75 N). Since the block is resting ont he lab bench, the bench exerts a force that is equal and opposite of Fg, lets call it Fn. The equation to calculate the force of friction is: Ff = uFn (where Ff is the force of friction, and u is suppose to be a mew, which is the coefficient of friction)

Now I'm a little iffy on this part, in calculating the force of friction, but your force of friction should be slightly smaller than 0.25N, because when you exert .25N of force to pull the block, you are over coming the force of friction. If you are doing Physics 20 I think you might be able to equate the two forces. I'll assume you are so Ff = 0.25N.

so u = Ff/Fn = 0.25N/1.75N = 0.1429

Like I said I'm not too sure if this is right, this how i would approach this. Hope this helps, lemme know if this is right.

[Gurpy]

Awesome, thanks for the help. I'm in physics 20 so that should do perfectly - I had the 0.25/1.75 put down on the lab but i'm pretty sure he wants us to draw the diagrams and all of that to show how we got to that so you probably saved my ass on this lab :) Thanks

I'll let you know if its right on Wednesday (usually we get the lab back a day after we hand it in)

[962 kid]

http://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/chapter5/2Chapter5/2Chapter5a.htm

at the bottom there is all you will need to know about friction... its not the answer (I'm too tired) but hey, if you wanted to you could do the lab yourself and actually get to know the stuff

[nismodrifter]

^OMG ZUBOT NOTES USED AS A REFERENCE FOR HELP!!!111! :rofl:

He does know what he's talking about though...crazy smart...can't teach worth shit.

[962 kid]

Originally posted by nismodrifter
^OMG ZUBOT NOTES USED AS A REFERENCE FOR HELP!!!111! :rofl:

He does know what he's talking about though...crazy smart...can't teach worth shit.


shhhhh ;) yeah he can't teach shit, but the stuff on there is a pretty good guideline haha

[nismodrifter]

I actually used his site a whole bunch of times when I was doing University physics, still have it bookmarked :D

[Gurpy]

Thanks for the link, ill be sure to bookmark it too :)

Same type of deal with my teacher - really smart, GREAT GREAT guy, but he sucks at explaining. If he was better at explaining he'd be a perfect teacher though.