Static and Kinetic Friction Lab Report PDF

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Genae Dixon 07/04/2020 Static and Kinetic Friction Lab Report  Introduction and Abstract: If you slide one object over the surface of another object, there will be a force opposing that motion. This resistance force is called friction and this force is parallel to surfaces. Friction is one of two contact forces, the other being normal force. There are many types of frictional forces, but the two most common types are static friction and kinetic friction. Static friction exists between surfaces at rest and kinetic friction exists between sliding surfaces or surfaces in motion. One method of evaluating frictional forces, defining the coefficient of friction, is found by the ratio of frictional force over normal force. This report explores and analyzes these frictional forces within different materials. The objective of these experiments is to determine if the coefficient of friction changes with load, and compare the coefficient of friction for various materials. Our goal is to determine the relationship between loads and frictional forces, determine the effects of surface area, and compare the effects of different materials.  Procedures: For part A of the experiment, we will  find the coefficient of static friction by raising a wooden plank to determine the angle at which the object begins to slide. For glass, Ceramic / Stone, RubberAcrylic, Brass, Steel, Copper, Nylon, and PVC cubes, we will Measure the coefficient of static friction for the wood block on the wood plank and Calculate the normal force, the force of static friction, and the coefficient of static friction for the average maximum angle of repose. For part B of the experiment, we will find the coefficient of kinetic friction for the wood on wood interface by applying various loads and determining how much force is required to bring the system to a state of constant velocity. We will measure  the kinetic friction force for six different loads on the block, calculate the normal force, the force of kinetic friction, and the coefficient of kinetic friction for each load. For part C we will do the same process as stated in part B, except the block will be on its narrow side to create data for a comparison of friction and surface area.             

Genae Dixon 07/04/2020 Data Tables, Calculations, and Analysis: Data Table for Part A – Static Friction On An Inclined Plane  Material

Trial 1 Trial 2 θ deg  θ deg 

Trial 3 θ deg 

Trial 4 θ deg 

Trial 5 θ deg 

Average Angle Std. Dev. Angle θ ave deg  σ θ deg 

Block

16.6

16.8

16.3

16.3

16

16.4

.308

Glass

18.9

19.1

19.2

18.8

20

19.2

.474

Ceramic

17.5

17.3

17.4

17.9

17.1

17.44

.297

Rubber

21.6

21.6

21.5

21.6

21.5

21.56

.055

Aluminum

17.4

17.6

17.5

17.5

17.8

17.56

.152

Brass

18

17.9

18

17.5

18

17.88

.217

Steel

19.4

20

19.6

19.6

19.5

19.62

.228

Copper

18.1

18

18

20

17.9

18.4

.897

Nylon

21.1

21

22

21.5

21.8

21.48

.432

PVC

18.3

19

18.4

18.3

18.4

18.48

.295

 Material

Mass m kg

Normal Force Force of static FN N friction Fs N

Coefficient of static Error in Static Friction δ μs  Friction μ s 

Block

.12573

1.18

.348

.294

.047

Glass

.05447 .505

.176

.348

.007

Ceramic

.03143 .294

.092

.314

.027

Rubber

.03798 .347

.137

.395

.054

Aluminum .04224 .395

.125

.316

.025

Brass

.1344

1.25

.405

.323

.018

Steel

.12719

1.18

.419

.356

.015

Copper

.14379

1.34

.445

.333

.008

Nylon

.02249 .205

.081

.394

.053

PVC

.01819

.057

.334

.007

.169

Genae Dixon 07/04/2020 Data Table for Part B – Kinetic Friction for Wood on Wood Mass of Block mB= .12573 kg

Mass of Hangar mH= .0100 kg Load mass Control Mass Normal Force Force of kinetic m1 (kg) mc (kg) FN (N) Friction FK (N)

Coefficient of Kinetic Friction μ k 

0

.20

1.23

.294

.239

.100

.035

2.21

.441

.200

.200

.060

3.20

.687

.215

.300

.075

4.18

.834

.200

.400

.090

5.16

.981

.190

.500

.115

6.14

1.23

.200









Average .207









St. dev. .017









% Difference 34.7%

Genae Dixon 07/04/2020

Data Table for Part C – Kinetic Friction and Surface Area Mass of Block mB= .12573 kg Mass of Hangar mH= .0100 kg Load mass Control Mass Normal Force Force of kinetic m1 (kg) mc (kg) FN (N) Friction FK (N)

Coefficient of Kinetic Friction μ k 

0

.020

1.23

.294

.239

.100

.035

2.21

.441

.200

.200

.065

3.20

.736

.230

.300

.075

4.18

.834

.200

.400

.095

5.16

1.03

.200

.500

.110

6.14

1.18

.192









Average .210









St. dev. .019









% Difference 33.3%







Part B %Difference 1.44%





Genae Dixon 07/04/2020    Conclusion: In these experiments, we explored how different factors impact the frictional coefficient of an object. In experiment A, we performed a simple run where we record the maximum angle needed to displace a material from its resting position. The data shows that different materials do impact the frictional coefficient of an object. The texture of the surfaces of objects may allow for more resistance than others. For experiment B, we varied the load carried by a wooden block sliding across a wooden surface on a pulley system. The trend in our data supports the idea that friction increases with load carried. Our graph’s trendline with a slope of .188 has a 9.6% difference from our friction coefficient of .207 in part B. In the pre-lab I predicted the y intercept to be 0, and the y-intercept is .0531, which means that frictional forces will exist even when normal force is at equilibrium (0). In experiment C, performed the same procedures as part B, but used the narrow side of the block. According to the data gathered in our experiment, surface area does not have a significant impact on the frictional coefficient. There is only a 1.44% difference from our data in part B. Overall we were able to conclude that different textures exert different frictional forces, surface area has an insignificant impact on frictional forces, and the frictional coefficient is proportional to load of an object....