[INTRO THEME PLAYS]
[Why are you singing it in your brain?]
In this experiment, we are going to find
out the coefficient of static friction
between paper and paper, paper and
sandpaper, paper and smooth book wrap,
paper and matte book wrap,
and lastly paper and Teflon. So the
procedure is simple first we are going
to cut up a piece of paper and wrap it
around a piece of eraser. Second the
eraser is put on an inclined plane
[ABRUPT PAUSE] Alright it's me *while editing the video. I
actually forgot to say that it was
inclined plane wrapped with paper, so
keep that in mind. The inclined plane is tilted
slowly until the eraser begins to slide.
The angle theta is recorded.
Steps 2 to 3 is repeated five times and
average reading of theta is calculated.
Coefficient of static friction is then
calculated using the formula below.
Finally step one design is repeated by
replacing the paper with other materials.
[SHAMELESS PLUG] Now if you haven't check out my last video about friction make sure you check
it out because I explained a lot about friction in that video. I will link it in my description.
Now I would like to talk
about how does the formula works. First
at all I would like to introduce a
formula that you probably already know if
you watched my previous video. Now
rearrange the formula to find the
coefficient of static friction. So from
here we know that the coefficient of
static friction is nothing but the
static friction divided by the normal
force. Now let me draw the free-body
diagram of the inclined plane in the experiment.
We know that Wx is equal to static
fiction because we want to calculate the
coefficient of static friction and Wx
is nothing but [BELL DING]
Now we want to express
the normal force in terms of theta. We
know that Fn is equal to Wy because
again we want to calculate the
coefficient of static friction and the
normal force is nothing but [BELL DING AGAIN]
Now substitute two and three into one
And we know that sine divided by cosine is
nothing but tangent. So the coefficient of
static friction is nothing but [BELL DING and PIANO MUSIC]
Now there are several precautionary step while
carrying out this experiment. First at
all we must move the inclined plane as
steady as possible. This is to prevent
any external force from acting on
the eraser. I found this hard to do so I introduce pulleys.
A pulley trade distance for force
[SAYING NONSENSE STUFF IN BACKGROUND]
OK what I mean here is I need to move a lot at the input and the output will just move a little bit
And protractor is no t very accurate
for this purpose so [BELL DING?]
Alright it's me again while editing the
video. So I actually don't mean that a
protractor is not accurate itself but
instead I mean the setup itself is fairly
unaccurate. First at all the
protractor can move around like this and
another reason is that it is very hard
to find origin of the slope so I would
rather stick with the digital protractor
instead and it will be much more
accurate.
And here is the result.
[WHISPERING] Oh wait, I think the result for Teflon is a little bit off.
Based on the
result the coefficient of static
friction between paper and sandpaper is
the largest, which is 0.54. This is
followed by paper and paper which is
0.39. And the next one was Teflon, which
was quite off. And smooth book wrap Finally matte book wrap.
Thanks for watching make sure you
subscribe like and share. And happy physicing!
