Physic report "Friction Force" by Fildia Putri as an apprentice in Makassar State University - Chemistry International Class Program

1. FRICTION FORCE
Fildia Putri, Rafika Sri Rahayu , Nul Lailah , Nurul Wisna Afianti, Nur Rahmah
Marisa Raden.
Departement of Chemistry, FMIPA State University of Makassar 2013
Abstract. Have done the experiment with title friction force. Purpose experiments to identify
factors that affect friction force, understand concept of static and kinetic friction, and
determine the coefficient of static and kinetic friction. Data obtained by using tools a pulley,
rope/yarn, spring balance, refined and coarse beams, board basis, inclined plane, stopwatch,
meter, and a square beam. First activities observed drag force against state object, activity 2
relationship between normal force to friction force, activity 3 relationship between state of
surface friction, activity 4 determine coefficient of static friction on incline, activity 5
determine coefficient of kinetic friction inclined plane. Collecting data on activities of first to
third activities that looked basically same tensile force on object is at montionless, precise to
move and uniform line motion only on activities that differentiate beams 1 and 3 used same
mass but also activities 3 use two different types of surfaces, activities 2 use same type of
surface and different normal force. While activities 4 determine critical angle of objects with
different gravity, activities 5 determine travel time by different mileage. So, conclusion of
this practicum is frictional force affected by normal force, coefficient of friction, critical
angle, and type of surface.
KEYWORDS: Friction force, article format, static friction force, kinetic friction force,
normal force, coefficient static friction,coefficient kinetic friction, condition object :
montionless, preciseto move, uniform line motion.
INTRODUCTION
In our daily activity we often find the application of frictional force. Two
objects that are touching each other which can cause it to rub against objects. Usually
friction between two surfaces that are touching each good in the air, water or solid
objects. Friction can be known through experiments with doing pengekuran.
Calculate the frictional force can be done by various methods, one of which is using
a spring balance, pulley, beam by calculating the tensile force keaadan object against
some good things in is at montionless, precise to uniform, and uniform line motion.
hen, using two different types of surface that is refined surface and a smooth surface
by calculating the tensile strength of the object at rest, precise to uniform and
uniform line which produces motion speed difference. In addition to these methods,
using the incline as the testers are used to calculate the friction coefficient of friction
coefficient of frictional force either static or kinetic frictional force coefficient which
has a value of critical angle and distance, as well as a stopwatch to calculate the
travel time object / beam to reach the end inclined plane.
Based on the above statement there is a question why the frictional force
influenced the state of objects at montionless, precise to uniform, and uniform line

2. regular ?. Answers to these questions are due at the time the object was montionless
objects do not experience frictional force because the force that occurs in a very
small objects or even no, continue when the precise thing would be uniform the
object will undergo static frictional force due to the force exerted on the object is
large enough that the object was uniform or the force exerted on an object is equal to
the frictional force occurs, and when the object uniform line motion objects having
kinetic frictional force due to the force applied is greater than frictional force that
occur so that the object was uniform motion line.
Then the next question is what is the formula to determine the static and
kinetic coefficient of friction?. The answer to the question which is to determine the
formula of the static friction coefficient using the formula (1) and to determine the
formula of the kinetic friction coefficient using the formula (2).
The classic rules of sliding friction were discovered by Leonardo da Vinci
(1452-1519), but remained unpublished in his notebooks. They were rediscovered by
Guillaume Amontons (1699). Amontons presented the nature of friction in terms of
surface irregularities and the force required to raise the weight pressing the surfaces
together. This view was further elaborated by Belidor (representation of rough
surfaces with spherical asperities, 1737) and Leonhard Euler (1750), who derived the
angle of repose of a weight on an inclined plane and first distinguished between
static and kinetic friction. A different explanation was provided by Desaguliers
(1725), who Demonstrated strong cohesion forces between the spheres of roomates
lead a small cap is cut off and roomates were then brought into contact with each
other.
The understanding of friction was further developed by Charles-Augustin de
Coulomb (1785). Coulomb Investigated the influence of four factors on friction play:
the nature of the materials in contact and their surface coatings; the extent of the
surface area; the normal pressure (or load), and the length of time that the surfaces
remained in contact ( time of repose). Coulomb Considered further the influence of
sliding velocity, temperature and humidity, in order to decide between the different
Explanations on the nature of the friction that had been proposed. The distinction
between static and dynamic friction is made in Coulomb's friction law (see below),
although this distinction was already drawn by Johann Andreas von Segner in 1758.
The effect of the time of repose was explained by Musschenbroek (1762) by
considering the surfaces of fibrous materials, with fibers meshing together, roomates
takes a finite time in the friction increases roomates.
John Leslie (1766-1832) Noted a weakness in the views of Amontons and
Coulomb. If friction arises from a weight being drawn up the inclined plane of
successive asperities, then why is not it balanced through descending the opposite
slope? Equally Leslie was skeptical about the role of adhesion proposed by
Desaguliers, roomates should on the whole have the same tendency to Accelerate as

3. to retard the motion. In his view friction should be seen as a time-dependent process
of flattening, pressing down asperities, roomates creates new obstacles in what were
cavities before.
Arthur Morrin (1833) developed the concept of sliding versus rolling friction.
Osborne Reynolds (1866) derived the equation of viscous flow. This completed the
classic empirical models of friction (static, kinetic, and fluid) commonly used today
in engineering.
The focus of research during the last century has been to understand the physical
Mechanisms behind friction. F. Phillip Bowden and David Tabor (1950) Showed that
at a microscopic level, the actual area of contact between surfaces is a very small
fraction of the apparent area. This actual area of contact, by the caused by " asperities
"(roughness) increases with pressure, explaining the proportionality between normal
force and frictional force. The development of the atomic force microscope (1986)
has recently enabled Scientists to study friction at the atomic scale[1].
At the time this trial is the friction experiments. The purpose of the
implementation of this experiment was to determine the factors that affect the
friction force, understand the concept of static and kinetic friction and determine the
static and kinetic coefficient of friction.
In the practicum, there are five methods of frictional force performed. Who
first observed the tensile force of the state of the object by using the same beam mass
to determine the tensile force on the object when the object was montionless, precise
to move, and uniform line motion. Second looked at the relationship between the
normal force to the friction force is the same surface normal but different force to
determine tensile force on the object is at montionless, precise to move and uniform
line motion. Similarly, the second practicum, the practicum looked at the relationship
between the state of the three surfaces with a friction force observed gravity objects
at rest, precise to uniform, and uniform line motion but the type of surface used the
refined and coarse surfaces. In the fourth practicum, determine the coefficient of
static friction on an inclined plane to calculate the critical angle of objects to
determine in advance determine the gravity of objects. And on the fifth practicum,
which determine the coefficient of kinetic friction on an inclined plane by first
determining the distance that must be traversed by the beam / objects to calculate the
travel time required to get to the end object of the incline with a stopwatch.
THEORY
Friction force is the force resisting the relative motion of solid surfaces, fluid
layers, and material elements sliding against each other[2]. Friction force includes a
stylish touch , which appears when two surfaces come into contact physical objects .
Direction of the force of friction with the surface of the touch pad in the direction
opposite to the trend and direction of motion.
Frictional force at work when things move in the air , water , or glide over
other solid objects . For objects moving through the air , the air friction force on an
object depends on the size of objects that come into contact with air . The greater the
bandwidth is greater touch of air friction force on the object . This concept is used by

4. the jumpers. When an object moves through the air , the surface of the object will be
in contact with air , causing friction between the object with air . Similarly, when
moving in the water. Friction force is also always occurs between the contact
surfaces of solid objects , even if the object is very slippery .Very slippery surfaces is
actually very rough on a microscopic scale . When we try to move an object , this
miskroskopis protrusions interfere with the motion . In addition , at the atomic level
(remember that all matter is made of atoms) , a bulge on the surface causes the atoms
are very close to the other surface , so that the electric forces between atoms can
form chemical bonds , as a unifying small among two moving surfaces . When a
moving object , for example when we push a book on a table surface , the movement
of the book have problems and eventually stop , because there is friction between the
bottom surface of the book with a table surface and the friction between the surface
of the book with the air , where the scale miskropis , this occurs due to the formation
and release of the bond . If the surface of an object with surfaces rub against each
other ,each of these objects do frictional force between each other[3].
There are two types of friction between two solid objects moving straight to
each other, the force of static friction and kinetic friction, which distinguished
between the touch points between the two surfaces is fixed or mutual change (shift).
Static friction is friction between two solid objects that are not moving relative to
each other. Coefficient of static friction is generally denoted by μs, and are generally
larger than the coefficient of kinetic friction. Static friction force generated from a
force that is applied just before the object is moving. The maximum frictional force
between two surfaces before movement is the result of the static friction coefficient
multiplied by the normal force. When no movement occurs, the frictional force can
have a value of zero to the maximum frictional force. Each style is smaller than the
maximum frictional forces trying to move one of the objects will be resisted by the
friction force equal to the force is large, but in the opposite direction. Every style that
is greater than the maximum frictional force will cause the movement occurs.Once
movement occurs , static friction force can no longer be used to describe the kinetics
of objects, making use of kinetic friction. Kinetic friction ( or dynamic ) occurs when
two objects move relative to each other and rub against each other. Coefficient of
kinetic friction is generally denoted by μk and are generally always smaller than the
static friction for the same materials[4].
A block is pushed on the table will move When a beam massm, we remove
the initial velocityVoon a horizontal plane , then the beam will eventually stop . This
means that in the beam movement slowed , or there is a force that holds the beam ,
this style is called friction. The magnitude of the frictional force is determined by the
coefficient of friction between the two surfaces of the objects and the normal force .
The coefficient of friction is determined by the surface roughness and objects.
Friction force divided into two : the static friction (fs) and kinetic friction (fk).
N
A block of weight W, is the rough horizontal plane , then pulled by force F as in
Image 1.1 below.
F
f
W
Image 1.1: The forces acting on the object.

5. f the friction force direction opposite to the force F causes , and apply :
1. For the price o F <fsthen beam it montionless.
2. For the price F = fsthen the beamprecise to move.
3. If phase enlarged so that F >fsthe moving objects and static friction
forcefswill turn into kinetic frictional forcefk.
Friction force between two surfaces mutually silent one against the other socalled static friction . The maximum static friction force is equal to the smallest force
needed to begin moving object . Once motion has begun , the friction force between
two surfaces is usually reduced so a smaller force is needed to keep things moving
irregularly . Force acting between the two surfaces move relative to each other is
called kinetic friction . If the big states fsthe maximum force of static friction , then :
fs
s
(1.1)
N
With s is the coefficient of static friction and the normal force N is large . If the big
states fkkinetic frictional force , then :
fk
k
with
k
(1.2)
N
iscoefficient of kinetic friction.
When an object is at rest on a flat surface , and then place the object plane is
tilted slowly to an angle right to object to the move, the coefficient of static friction
between the object and the field is given by the equation ,
S
= tan
(1.3)
c
With cis the angle at the right things will move , called the critical angle .
Coefficient of static friction is the tangent value of the angle of the field , with the
appropriate state object will move / slide . At angles greater than c , uniformly
accelerated beam sliding into the lower end of the inclined plane with acceleration:
ax
g (sin
k
cos
)
(1.4)

6. where is the angle of the field and k is the coefficient of kinetic friction between
the object plane.By measuring the acceleration ax, so coefficient of friction kcan be
measured.
EKSPERIMENTAL METHODOLOGY
Before doing practicum of friction force we first need prepare necessary
equipment and material in the practicum. The equipment and material are 0-5 N
spring balance, pulley table, the beam has two surfaces with a surface that is coarse
and refined surfaces, weight 50 grams and 100 grams, string / yarn, board basis,
inclined plane, which has a square beam with connective stecker, stopwacth, and
gauges as well as writing equipment.
Furthermore, the variables identified in this practicum. At first activities
practicum observing tensile force of the state of objects, while the variable object
manipulation is objec then the variable response of these activities and the tensile
force control variable is the mass of the beam. Operational definition of variables 1
praktium activities that manipulation of state variables of objects that always be
changed from a state of montionless, precise to move and uniform line motion
impact on the response variable gravities constant changes of 0.5, 1.6 and 1 , 2 and
the control variables are fixed with the beam of mass 1.9 N.In the practicum
activities 2 which looked at the relationship between the normal force with friction ,
variable object manipulation is the normal force and the state of objects then this
activity is the response variable tensile force objects and variables that control the
type of surface used . Operational definition of the variable activity 2 state
manipulation of objects at montionless then precise to move and uniform line
motiom , normal force object further changed by adding to the burden on the body
with a load of 50 grams , 100 grams and 150 grams so the normal force of the object
different , ie the manipulated variable gravity objects will change but , tensile force
on the object stationary object remains the same object then a tensile force on the
state of precise to move and uniform line motion has increased every change of the
normal force of the object , and the control variables type of surface used is slippery
surfaces. In the practicum activities 3 that looked at the relationship between the state
of the surface friction conditions, variable manipulation is a type of surface and the
state of objects, the response variable tensile force objects and variable control of this
activity is the normal force object. Operational definition of the variable activity 3
the manipulation variable surface types interchangeable with each measurement done
with 2 types of surface used is a coarse surface and refined surface and the state of
the object at montionless precise to move then and uniform line motion, then control
variables the normal force on the first object must be weighed with a weight of 1.9
N.In the practicum activities 4 to determine the coefficient of static friction on an
inclined plane, variable manipulation is gravity, the response variable is the critical
angle and the control variable is the incline. Operational definition of variables 4
activity, variable gravity object manipulation is used without the addition of the load,
and the added burden of 50 grams, 100 grams and 150 grams, the response variable
critical angle undergo constant change with increasing gravity of the object and
control variables was inclined plane using a bow.In the practicum activity 5 to
determine the coefficient of kinetic friction on the incline, while the manipulation is

7. variable distance traveled, this activity is the response variable of time traveled to the
control variable load mass and the angle of the field. Operational definition of
variables 5 activities, the manipulated variable is the distance traveled used from a
distance of 70 cm, 90 cm, and 110 cm with of time traveled of the response variable
objects constant increase distance traveled each object, and the control variables are
used the load mass 1, 1 N and the angle of the field with an angle of 30 º.
The working procedures of each practicum activities. Work procedures
practicum activity 1, things that must be done, namely provide beams, rope / yarn,
spring balance, and subsequently pulley rope all equipment that have been provided
and place it on a table that has a flat surface. First weighed the mass of objects /
beams are used, then slowly pull the spring with a small force to the object / beam
was montionless spring balance and record the appointment on the observation table,
then slowly pull the spring until it is the precise to move thing to move further appeal
spring back slowly until the beam uniform line motion and recorded appointing
straight spring in the table of observations.
Work procedures practicum activity 2 , which need to be prepared are the
same equipment in activity 1 but added weight 50 grams and 100 grams and do not
forget to weighed beam along a predetermined load, and then assemble the
equipment and the added weight above 50 grams the next beam slowly pull spring
with state montionless objects, precise to move until uniform line motion and
recorded appointing each spring every situation, they change the observation, but
repeat it loads on beams replaced ditambahan menjadi100 grams and 150 grams then
record the results of the appointment of the spring in the table of observations.
Work procedures for practicum activities 3, it needs to be prepared before
doing practicum beam with two coarse surfaces and the surface refined, spring
balance, the pulley, the next cluster tool into one. First use a beam with a refined
surface beam, pull spring slowly starts from the state of the object was montionless,
precise to move until uniform line motion and record the results in the table
designation spring observations, the same thing is done on the coarse surface of the
beam.
Furthermore, work procedure on the practicum activities 4, as for the things
that need to be prepared that the inclined plane is equipped with a bow, beam /
objects, weight 50 grams, 100 grams and 150 grams. Then assembles all of these
tools into one entity, then beam that does not put added strain on one end of the field,
then gently lift the tip area of a square beam is increased so that the angle of
inclination objects and record exactly when the object precise to move in the
observation table . The same is done on the beam that has been added burden of 50
grams, 100 grams and 150 grams.
At practicum activities 5, equipment used in the activities of 4 is basically the
same but the additional load is not used in this activity simply using a fixed mass
load, the bar and use stopwacth. Then adjust the angle of the field with an angle
greater than the critical angle obtained in section 1 above for a square beam with no
additional load and record the slope angle and adjust the distance / length of track to
be traversed beam of 70 cm, 90 cm and 110 cm.Further putting a square block at the

8. upper end of the known length of the field in advance of the starting length of 70 cm
and release along with running stopwacth beam to measure the of time traveled a
square beam moves uniformly accelerated up to the lower end of the field and record
the of time traveled on the observation table . Do the same at a distance of 90 cm and
110 cm and record the of time traveled it takes the beam to get to the lower end of
the field.
EKSPERIMENTAL RESULTSDAN DATA ANALYSIS
1. EKSPERIMENTAL RESULTS
A. Activity 1
Mass of beam =
Least scale of spring balance
Mass
= 10
m=
10 = 5
N
= 0,1
N=
0,1 = 0,05
Table1.1Observation result of influence the pull force toward an object
No
Pull Force (N)
Object Condition
Montionless
1
Precise to move
2
Uniform line motion
3
B. Activity 2
Kind of the surface is refined
Table 1.2.Relation between pull force with normal force
No
Normal
Force
Pull Force (N)
Object
Condition
(N)
Measure
Montionless
Precise to move
1.
2.
1
3.
Uniform line
motion
1.
Average

9. 2.
3.
Montionless
Precise to move
1.
2.
3.
2
Uniform line
motion
1.
2.
3.
Montionless
Precise to move
1.
2.
3.
3
Uniform line
motion
1.
2.
3.
C. Activity3
Normal Froce =
Table1.3. Relation between kind of surfacewithPull force
Kind of
Object
Pull Force (N)

10. Surface
Condition
Measure
Average
Montionless
I
Precise to move
1.
2.
Refined
3.
Uniform line
motion
1.
2.
3.
Montionless
II
Precise to move
1.
2.
3.
Coarse
Uniform line
motion
1.
2.
3.
D. Activity 4
= 1o/scale
Table 1.4. Static friction force at the aslant area.
=
1o = 0,5o/scale

11. Critical Angle (0)
Weight force
No
(N)
Measure
1.
o
2.
o
2.
o
3.
o
1.
o
2.
o
3.
3
o
1.
2
o
3.
1
Average
o
o
o
o
E. Activity 5
Mass of load =
Least scale of stopwatch = 0,1
Declivity of angle area = |30,0 0,50|
= 0,05 s/scale
Table 1.5. Kinetic friction force at the aslant area.
Time (s)
No
Mileage (cm)
Measure
1.
1
2.
3.
2
1.
Average

12. 2.
3.
1.
2.
3
3.
2. DATA DAN GRAPHIC ANALYSIS
A. Activity 1
1. Images the forces acting on the body when condition the object is at mentionless,
precise to move and uniform line motion.
F
W
(a)
a
N
N
N
F
F
s
µk
W
(b)
W
(c)
Image 1. The forces acting on the object (a) mentionless, (b) precise to
move, and (c) uniform linemotion.
B. Activity 2
Table: 2.1.Relationship between the normal force and friction force.
Normal Force
Friction Force
(N)
(N)
Static Friction Force (
(N)
Kinetic Friction Force
(N)

13. Table: 2.2.Relationship between the normal force and coefficient of friction force.
Normal Force
Coefficient of Friction Force
(N)
Coefficient Static Friction
(
Coefficient Kinetic Friction
(

14. For static friction force :

15. Static Friction Force (N)
3
y = 0.542x + 0.74
R² = 0.991
2.5
2
1.5
1
0.5
0
0
0.5
1
1.5
2
2.5
3
Normal Force (N)
Graphic 1.1.Relationship between the normal force and
static friction force
Truth degree
Relative Error
3.5
4

16. For kinetic friction force :

17. 8
Kinetic Friction Force (N)
7
y = 4.264x - 7.965
R² = 0.918
6
5
4
3
2
1
0
0
0.5
1
1.5
2
2.5
3
3.5
Normal Force (N)
Graphic 1.2.Relationship between the normal force and
kinetic friction force
Truth degree
Relative Error
4

18. C. Activity 3
Coefficient Friction Force
Coeffient static friction
Coefficient kinetic friction
Tabel: 2.3.Relationship between the coefficient of friction force every surface with
friction force.
Types of Surface
Coefficient of friction force
Coefficient static friction
Coefficient kinetic friction
(
(
I
Refined
1,46
1,21
II
Coarse
1,67
0,96
Uncertainly
Static Friction Force
Relative Error

19. Truth Degree
Relative Error
Kinetic Friction Force
Truth Degree

20. Relative Error
Truth Degree
Relative Error
Truth Degree
D. Activity 4
Coefficient Static Friction

21. Relative Error
Truth Degree

22. Relative Error
Truth Degree

23. Relative Error
Truth Degree
Tabel: 2.4.Relationship between the mass of load and coefficient static friction.
The Mass of Load
Coefficient of friction force
(Gram)
Coefficient static friction (
160
210
260
E. Activity 5
0,3699
0,300
0,2735

24. Quadrate of time traveled (s)
2.5
y = 0.016x + 0.278
R² = 0.998
2
1.5
1
0.5
0
0
20
40
60
80
100
120
Distance Traveled (cm)
Graphic 1.2.Relationship between the quadrate of time
traveled (t2) and distance traveled (s).
Truth Degree
Relative Error
Analysis Calculation
140

26. Relative Error
DISCUSSION
Based on the results of experiments that have been carried out as for the discussion
of each activity that is the first to observe the activities of the state precise tensile force by
observing the tensile force precise at montionless, object to uniform, and uniform line
motion. At the time of montionless objects tensile force 1.5 N precise it shows that the
friction force that occur in only a few precise so that the object remains montionless, when
the object precise to uniform tensile force that arises in 1.8 N precise that prove force given
on precise large enough to be able to uniform or experience static friction force and the last
state of that is uniform motion line with a constant state of tensile force is 0,8 N precise so
that the kinetic friction force caused by tensile force beams that arises from friction with the
surface of the table.
In the second activity that looked at the relationship between the normal force with
the frictional force on the state of montionless objects, precise to uniform and uniform
motion line, but at montionless objects do not happen so that data can be compared when the
object to uniform precise and uniform line motion. On the precise to uniform the object
experiences a force of static friction with normal force different from the 1,90 N, 2.40 N and
3.40 N static friction force increases, it indicates that if the normal force of the object that the
static friction also great because there are forces on the object so large static friction
increased by the addition of the normal force.Further, when the state of the object uniform
motion line experiencing kinetic friction that has the addition / expansion of the force that

27. the object was uniform. As with the static friction with normal force that increasingly
enlarged the static friction of the object was also increased.
Later in the third activity that looked at the relationship between the state of the
surface of the friction force on the state of montionless objects, to uniform precise, and line
beergerak irregular use two types of surfaces are a refined surface and rough surfaces. On a
refined surface gravities occur in objects / beam is greater than the tensile force occurs on the
surface of the rough on the precise two-state object to uniform and uniform line motion it is
because the rough surface of the friction forces that pull required smaller so that objects
uniform on a refined surface, while friction force is smaller so that the required tensile force
greater that the object was uniform. In the graphic the activities can not be made because no
comparative data.
Then the four activities that determine the coefficient of static friction on an inclined
plane using a different gravity of the beam / load observed critical angle formed when the
object has gravity 1,6 N, 2,1 N, and 2,6 N. In the first gravity is greater than the critical angle
with gravity objects 2,3 and 4. From the experimental results it can be seen that the greater
the gravity of a beam / object that formed the critical angle is getting smaller because of the
attraction was the great object due to gravity or sooner reached the end of the incline than the
gravity that affect the state of the beam.
And the Last activities of the five events, which determine the coefficient of kinetic
friction on an inclined plane that uses a different distance and angle of the beam remains
fixed and the mass. Based on the experimental results showed that at 84 cm distance objects
travel time to get to the end of the incline is less than the distance of 104,3 cm, and 124 cm.
So, the closer the object of the incline the travel time it takes the less.
The factors that affect the friction force is the normal force object, gravity, tensile
force, good thing it's kind of surface rough surface or smooth surface, but it also
dipengaaruhi friction force by the state of things at the time the object was silent but silent
when friction force objects are very small or none at all, at the time the object was precise to
uniform objects having static friction force, and when the object was uniform line
experiencing motion objects kinetic friction force.
Friction consists of two, namely static friction force and kinetic friction force. Static
friction occurs when the object to uniform in the precise circumstances because the force that
occurs at the same object with friction force. Kinetic friction occurs when a uniform object
in a state of motion line because the force object that happens to be greater than the friction
force experienced by objects / beam. In the known friction force coefficient of friction force.
Coefficient of friction force consists of two, the coefficient of static friction and kinetic
friction coefficient. As for how to determine the static friction coefficient can be determined
by the formula (1) and to determine the coefficient of kinetic friction can be determined by
the formula (2).

28. CONCLUSION
Friction force is the force resisting the relative motion of solid surfaces, fluid layers,
and material elements sliding against each other.Friction force includes a stylish touch ,
which appears when two surfaces come into contact physical objects . Direction of the force
of friction with the surface of the touch pad in the direction opposite to the trend and
direction of motion. Frictional force at work when things move in the air , water , or glide
over other solid objects.
There are two types of friction between two solid objects moving straight to each
other, the force of static friction and kinetic friction, which distinguished between the touch
points between the two surfaces is fixed or mutual change (shift).Static friction is friction
between two solid objects that are not moving relative to each other. Coefficient of static
friction is generally denoted by μs, and are generally larger than the coefficient of kinetic
friction.Kinetic friction ( or dynamic ) occurs when two objects move relative to each other
and rub against each other. Coefficient of kinetic friction is generally denoted by μk and are
generally always smaller than the static friction for the same materials.
The factors that affect the friction force is the normal force object, gravity, tensile
force, good thing it's kind of surface rough surface or smooth surface, but it also
dipengaaruhi friction force by the state of things at the time the object was silent but silent
when friction force objects are very small or none at all, at the time the object was precise to
uniform objects having static friction force, and when the object was uniform line
experiencing motion objects kinetic friction force.
Friction consists of two, namely static friction force and kinetic friction force. Static
friction occurs when the object to uniform in the precise circumstances because the force that
occurs at the same object with friction force. Kinetic friction occurs when a uniform object
in a state of motion line because the force object that happens to be greater than the friction
force experienced by objects / beam. In the known friction force coefficient of friction force.
Coefficient of friction force consists of two, the coefficient of static friction and kinetic
friction coefficient. As for how to determine the static friction coefficient can be determined
by the formula (1) and to determine the coefficient of kinetic friction can be determined by
the formula (2).
Andtofindthe acceleration ofthefrictional forcewecanusethisformula:
ax
g (sin
k
cos
)

29. REFERENCES
[1]Anomin. 2013. History. http://www.tribology-abc.com/abc/history.htm. Accessed at :
Sunday, 10 November 2013, 11.00.
[2]Anonim. 2013. Friction. http://en.wikipedia.org/wiki/Friction. Accessed at : Monday, 11
November 2013, 16.34.
[3]Husna.2011.Laporan
praktikum
fisika.
http://gusnablogspotcom.blogspot.com
/2011/06/laporan-praktikum-fisika.html. Accessed at : Monday, 11 November 2013, 15.22.
[4]Septiawan. 2013. Laporan fisika. http://setiawanfiles.blogspot.com/2013/04/laporanfisika.html.
Accessed
at
:
Monday,
11
November
2013,
15.01.