Coefficient Of Friction

Coefficient of Friction Syeda Wasti Lab Partners: Soorya Deepak Joseph Piaubert Roa Zeyna SP1XB-02

Abstract The purpose of this lab is to determine the coefficient of friction for wood on synthetic stone and felt on synthetic stone.

Introduction Friction is the force between surfaces in contact that resists the relative lateral (tangential) motion. Static friction is the resistance a stationary object must overcome in order to be set in motion. Kinetic friction is resistive motion on an object that is already moving. The coefficient of friction is the ratio between the weight of an object being moved along a surface and the force of friction: ƒ = μN. The coefficient of friction depends on the surfaces in contact and is directly proportional to the normal force.

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Diagram

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Procedure Write a brief description of the activities you performed during the lab. Gathering or putting away equipment, entering numbers in a table, calculating results, and writing a report are not lab procedures. Use bullets if you like. Something like this… 1. Configure LoggerPro; start with the wooden side of the block facing the stone top of the table; hook the motion sensor onto the block 2. Gather masses and weigh them, weigh the wooden block 3. When beginning each trial make sure the motion sensor’s hook is not pulling on the block, so that there is no tension before you start to move the block, and “zero” the scale 4. Click “collect” and begin to pull the motion sensor backwards at a constant velocity 5. Click “stop”; you now have a graph of force over time. Click “stats” and record the max value (static friction). Highlight the section on the graph that looks the most like a horizontal line. Click “stats” to get the mean (kinetic friction 6. Repeat steps 2-4 with 10 different trials making sure to have a different mass each time. Make sure to add the weight of the wooden block to each trial along with the added masses. 7. Repeat steps 2-6 but with the felt side of the block facing the table.

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Analysis F Max was a measure of static friction and F ave was a measure of kinetic friction. Wood on Stone Trial

Mass (kg)

Weight (N)

F Max (N)

F ave (N)

1.

0.602

5.90

1.749

1.507

2.

0.461

4.52

1.729

0.793

3.

0.605

5.93

2.477

1.467

4.

1.105

10.8

3.544

2.412

5.

0.264

2.59

0.5285

0.039

6.

0.620

6.08

1.627

0.801

7.

1.461

14.3

5.157

2.920

8.

0.605

5.93

2.118

0.843

9.

1.258

2.53

1.831

0.602

10.

0.958

9.39

4.314

1.962

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Felt on stone Trial

Mass (kg)

Weight (N)

F Max (N)

F ave (N)

1.

0.461

4.52

1.530

1.087

2.

1.105

10.8

3.789

2.822

3.

0.605

5.93

1.326

0.883

4.

0.602

5.90

1.743

1.304

5.

1.602

15.7

4.637

3.346

6.

1.102

10.8

3.315

2.331

7.

0.958

9.39

2.702

2.023

8.

1.958

19.2

5.672

4.152

9.

2.617

25.6

7.09

5.680

10.

1.605

15.7

4.717

3.429

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Conclusion Coefficients of friction Static (N)

Kinetic (N)

Wood on stone

0.281 ± 1.90

0.223 ± 1.51

Felt on stone

0.223 ± 1.51

0.281 ± 1.90

Sources of Error The motion sensor was not moving at a constant velocity and there was already some tension force between the motion sensor and the wooden block.

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