Introduction
The polygon of forces represent lot of forces leading in a simultaneously to one point so all this forces acting will make a figure or they are call Vector such as force, that has magnitude and direction and can be resolved into components that are odd functions of the coordinates.
“A vector is a directed at an angle to the horizontal (or the vertical) can be thought of as having two parts (or components). That is, any vector directed in two dimensions can be thought of as having two components. For example, if a chain pulls upward at an angle on the collar of a dog, then there is a tension force directed in two dimensions. This tension force has two components: an upward component and a rightward component. As another example, consider an airplane, which is displaced northwest from O’Hare International Airport (in Chicago) to a destination in Canada. The displacement vector of the plane is in two dimensions (northwest). Thus, this displacement vector has two components: a northward component and a westward component.”
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“Newton law variety of ways by which motion can be describedwords, graphs, diagrams, in this unit Newton’s Laws of Motion the ways in which motion can be explained will be discussed. Isaac Newton a 17th century scientist put forth a variety of laws, which explain why move objects or don’t move as they do. These three laws have become known as Newton’s three laws of motion. The focus of Lesson 1 is Newton’s first law of motion.”
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Method
Attaching four lengths of strings to the pulley of fine cord and adjusting the weight of F1: 850g F2: 800g F3: 800g F4: 800g to the maximums to the string and them put a sheet of paper record all the line on the sheet of paper to help you to do all the calculation did this experiment.
Results
The values was in grams so this values as to be convert to Newtown so to convert kilogram to Newtown you multiply by the value in kilogram by 9.81
My value are F1: 850g = 0.85kg ´ 9.81 = 8.34N
F2: 800g=0.80kg´ 9.81 =7.85N
F3: 800g=0.80kg´ 9.81 =7.85N
F4: 800g=0.80kg´ 9.81 =7.85N

X axes

Y axes

F1= 8.34N cos 42°= 6.20N

F1= 8.34N sin 42°= 5.58N

F2= 7.85N cos 136°= -5.65N

F2= 7.85N sin 136°= 5.45N

F3= 7.85N cos 224°=-5.65N

F3=7.85N sin 224°= -5.45N

F4= 7.85N cos 313°=5.35N

F4=7.84N sin 313°= -5.74N

SFx= 0.25N

SFy= -0.16N

R = 0.192N angle q =20°
Discussion
This results are equilibrium but they was same human error that’s why the results are not equal to zero but it ok so the percentage error of are 0.41%.
These lines of action produce a closed polygon that’s why a drawing of polygon of forces as been draw from head to tail to prove that the result of this equation and the drawing as a result angle of 20°.
The analytic of forces show that these forces are equilibrium but the result shows that there is an error in the calculation this error is duo to loose of fiction, this can happen by the loop move or human error.
The possibility of losses friction experiment are the pulleys when it running can cause losses of friction, the cable was use in this experiment could be one of problem is well and another possibility is that the person ho transfer the line in to the sheet of paper did not mark the follow the line.
Looking to this experiment the difference between static friction and kinetic friction is that static friction when it applied force is less than the limiting friction, the body remains at rest It is the friction experienced by a body, when it is at rest, or when the car is at full stop or not moving.
Kinetic friction When it applied force exceeds the limiting friction the body starts moving over the other body and the Friction of resistance experienced by the body while moving and if you are running for you to stop kinetic friction will apply.
FRICTION
Frictions can benefits to our life because friction it happen to Olmos every think we do in our daily life, exp: when pushing a baby pushchair these friction there, when we slip friction is there, when we shaking hands friction is there to and it important uses in some situations, friction is very important and beneficial. There are many things that you could not do without the force of friction. Friction and weight are common experiences and taken for granted, but were not always understood. Aristotle believed that objects that contained earth fell because in Earth was at the center of the universe, and that was the natural order of things. We know that weight, which is the force of gravity between objects, not only makes apples fall from trees, but keeps the Moon circling the Earth, and the Earth circling the sun. Aristotle also believed (and some students still believe) that the natural state of an object is to be at rest. That is, without a force pushing it, an object will slow down to a stop. This view overlooks friction, which is the force that causes most objects we see to come to rest. Now we know that there is nothing pushing planets along their orbit, and that without gravity to hold them in orbit, they would continue to move in a straight line until interfered with Friction.

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The disadvantage of friction is that you could not walk without the friction between your shoes and the ground as you try to step forward; you push your foot backward Friction holds your shoe to the ground, allowing you to walk Consider how difficult it is to walk on slippery ice, where there is little friction when you playing a football match it makes friction and friction also cause as to use lot of energy so we are playing a big object on friction Writing with a pencil requires friction You could not hold a pencil in your hand without friction It would slip out when you tried to hold it to write The graphite pencil led would not make a mark on the paper without friction.
A pencil eraser uses friction to rub off mistakes written in pencil lead Rubbing the eraser on the lead wears out the eraser due to friction, while the particles worn off gather up the pencil lead from the paper.
The means of reducing friction when moving a large object is that if two people move the object with the same forces they will be less friction and you need to reduce friction between the box and the tile floor so that you can move the box easy, you can increase friction on your shoes to help you move the box.
Static friction
Static friction is friction between two solid objects that are not moving relative to each other. For example, static friction can prevent an object from sliding down a sloped surface. The coefficient of static friction, typically denoted as μs, is usually higher than the coefficient of kinetic friction.
Kinetic friction
Kinetic friction occurs when two objects are moving relative to each other and rubs together (like a sled on the ground). The coefficient of kinetic friction is typically denoted as μk, and is usually less than the coefficient of static friction for the same materials. In fact, Richard Feynman reports, “with dry metals it is very hard to show any difference.” Finally, new models are beginning to show how kinetic friction can be greater than static friction.A surface can always supply a normal force, perpendicular to the surface. However, a surface quite often also supplies a fiction force parallel to the plane. Friction forces always oppose the motion — or prevent the motion.
Conclusions
Friction is necessary in many ways to prevent slipping or sliding but also, it can be a nuisance because it can affect many thinks in our life by in reality friction is very important, in this report the very important key is that the experiment went well as according to plan the calculation was correct but the was a small error in the all project that we count prove that this equation was equilibrium but the error did came from many ways exp: human error and many thinks.
References
http://www.physics247.com/physics-homework-help/dynamics8.jpg
http://en.wikipedia.org/wiki/Static_friction