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David Mortimer
Physics Teacher
Del Rio High School
SFDR-CISD
Haiyan Yang, Ph.D.
Xinghang Zhang, Ph.D.
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Specific Application of
Technology
◦ The concept of the
application of material
onto another surface to
change or enhance, aka.,
exploit, materials.
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Future applications
-The how and why of
Vacuum Systems to
include the gas laws.
-The stacking of
atomic crystal
structures.
-Testing of material
properties.
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TEKS
B1-4, Conducting field and
lab experiments, building
knowledge by physical,
mathematical, and
conceptual models,
understanding the whole,
Investigations led to
changing understanding.
C,1,a,b, Lab Safety
C,2,a-e, use scientific
method
C,3,a-d, critical thinking and
problem solving.
C,4,a, laws governing motion
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TAKS
Objective 1, The nature of
Science
Objective 5, Motion, Force,
and Energy
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1.
2.
3.
4.
Pre-Testing
Before starting this lesson the teacher would have covered the following:
Changes in Motion
a. Force is a vector quantity that causes changes in motion.
b. Force can act either through the physical contact of two objects or at a
distance.
c. Free body diagrams.
Newton’s first law
a. “Law of inertia”-nothing will change what it is doing unless a net force>0
acts upon it.
Newton’s second law
a. Force = mass X acceleration
Newton’s third law
a. Rocket law – for every action there is an equal and opposite reaction.
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Students will be asked to come up with a plan
to test certain materials that are applied to
other materials so that they can test for the
best reduction in friction.
Students will be shown situations where the
least friction will be of benefit to a consumer.
Students will compete for longest slide at the
end of the lab experience.
XYZ Skateboard Co.
Application for bids
Dear Valued Future Vendor:
XYZ Skateboard Company is accepting bids for a thin film product that will lessen the
coefficient of friction on our line of very popular skateboards. XYZ Skateboard began
in 1992 and has been know from the very beginning to be an innovator in skateboard
design. This process is expected to be very competitive and the chosen bidder will
likely reap financial and personal reward.
Since we believe in the common man and his innovative ability, the following is
provided to help you, the bidder, to better understand the concepts that we are dealing
with. We will be offering a class where you may learn to test for the coefficient of
friction, how hard is it to get something to move, and, also, you may test your own
samples in our state of the art testing facilities.
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The goal of this lab is to determine the static and kinetic coefficient
of friction for various materials in contact with one another and then
apply a coating of some other materials to determine if the
coefficient increases or decreases.
The student will also try to show the effect of increased mass,
increased/decreased surface contact, changes in the angle of the
inclined board, and changes in velocity.
The student will also be making conclusions about which materials
work best together in different situations.
The student will be asked to rank your findings and a contest for the
best sliding mixture of materials will occur at the completion of the
lab.
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Fourier Lab Pro Data
loggers
Distance Sensor
Force Sensor
4’ shelf
Ring stand
Set of masses
Aluminum block
Steel block
Brass block
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3-Petri dishes
Clamp
Protractor
Meter stick
Graphing calculator
Balance Scale
Teflon Spray
Silicon spray
Graphite
String
1)
2)
3)
4)
5)
Clean up your block so that it has the least amount of
friction.
Place wax paper onto the scale and zero out the scale.
Find the mass (m) of the first block.
Place the first block into the set up.
Calculate Fgrav=m*ag and enter into the data sheet.
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If the weight is on an incline, the normal force will be reduced by the cosine of the incline angle. The
equation is
N = wcos(a)
where:
N is the normal force on the incline
W is the weight, weight is a force, the force of gravity, Fgrav=mass*acceleration of gravity.
a is the incline angle
cos(a) is the cosine of the angle a
Wcos(a) is W times cos(a)
6)
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10)
Calculate the normal force, Fnormal=Fgrav *cosΘ and
enter into the data sheet. Cos (0) = 1
Connect the force sensor to the string and pull, note
what the force is when the sample starts to move. This
is your Fapplied. Enter into the data sheet.
Pull the mass again with constant velocity, enter the
force required to keep the block moving.
Replace the block onto the board and raise the board
until the block begins to slide. Note the angle at which
the block began to slide.
Calculate the Fnormal using your new angle.
11)
12)
13)
14)
Repeat steps 3-10 for each set of blocks.
We are now going to apply a thin coat of three different
materials, Teflon spray, Silicon spray, and graphite to see
how these coating affect the coefficient of friction. It is very
important that you clean the sample very well after each
application of material.
Place the first sample into the Petri dish with the graphite.
Move it around to completely cover the bottom of the
sample. We want a thin film. Excess material should not be
evident. The thinner the layer the better.
Repeat steps 3-10 using the new film and note your results.
Material A/mass/
position/coating if
applicable
Material
B
Ex., aluminum,
.5N,wide side
forward, no coat
Wood
Shelf
Ex., Aluminum,
thin side
forward,.55N,
Graphite
Steel bar
Fgrav
=mag
Applied force
to start
movement
Applied force
to maintain
movement
Fstatic friction
FKineticriction
Calculated
FNormal=Fgrav
*cosΘ
Angle
of
board
Fnormal
on
angle
Calc
µStatic= Fstatic
friction/ FNormal
Calc
µkinetic= Fkinetic
friction/ FNormal
Static Force
Kinetic Force
Force
Distance
40
257
41
280
F=k*distance
48
47
y = 0.0238x + 34.184
R2 = 0.9934
46
42
327
43
365
44
413
45
446
46
489
40
47
550
39
Force
45
44
Linear ( )
43
42
41
0
100
200
300
Distance
400
500
600
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Post Testing
Student should have mastered the concepts presented in the pre-testing phase.
Newton’s laws and Force Diagrams
The student should have a clear understanding of the difference between static and
kinetic friction. The student should be able to determine the coefficient of static
friction.
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The student should be able to make informed choices given information about
coefficients of friction to choose the right supplies for the right job.
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Students should realize that they do not need sophisticated equipment to determine
forces.
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Most importantly, students should realize that they have seen these concepts all of their
lives and realize that we are only reinforcing what they already know.
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Generally, what is the normal force?
What is the applied force?
When does something begin to slide?
Why does it not slide originally?
Is the normal force more or less when the board is inclined?
What helps make it slide when it is on an incline?
Is the µkinetic ever bigger than the µStatic?
Why don’t we consider air resistance?
Draw a free body diagram of the horizontal plane and another one for the
angled plane. Label all forces that are applicable.
Is the coefficient of friction constant depending only on the types of surface
in contact? (Remember it is very difficult to reproduce exactly the same value
for the coefficient of friction on each run.)
Does the surface area, positioning, change the coefficient of friction?
Explain.
Does the normal force change the coefficient of friction?
What are your sources of experimental error?
Xinghang
Zhang,
Ph.D.
Haiyan
Wang,
Ph.D.
Joon Hwan
Lee Optical ,
transparency,
transmittance
South Korea
Jie (Joyce)
Wang High
Temperature
Super
Conductor
3/21/2016
Roy Araujo :
Functional
Nitride Thin
Films
Peru
Ick Chan
Kim
Prop. Of
film
through
thickness
change
South
Korea
Harrison
Tsai
same as
Joyce
Jong Sik
Yoon
Functional
Oxide Thin
Films
South
Korea
Sunmee
Cho,
South
Korea
Zhenxing
Bi
Deposition
Patterns
China
Acknowledgements
I am thankful to the
following
National Science Foundation
All of the TAMU faculty and
Staff
Texas A&M Giggem Aggies
Dr. Wang and Dr. Zhang
Zhenxing Bi Ph.D. Candidate
Joon Hwan M.S. Candidate
All of the rest of the Pulsed
Laser Deposition laboratory
candidates
Ms. Crystal Woods
All of the E3 Participants
Dixie Chicken