Justin Geeslin
Eng Physics I - M 1:00
Experiment Seven – Static and Kinetic Friction
Introduction
This experiment demonstrates the effects of static and kinetic friction upon an object on a flat surface. In this experiment, a wooden block filled with varying weights will be dragged across a plane by a Force Sensor. The sensor will provide data to the computer to produce a graph mapping the varying levels of friction. The friction will increase as the mass of the block increases.
Procedure
First, ready the computer to process the input from the Force Sensor. In Logger Pro, open “Exp 12DR” from the Physics with Computer directory. Next, get a precise weight of the wooden block. It should be similar to the data below. Before every trial it is important to zero the Force Sensor each time. Once zeroed, the Force Sensor will provide an accurate read out of both the static and kinetic friction experienced by the block on the table. There will be 3 trials per different weight. The different weights include adding 250g, 500g, 750g, and 1000g to the mass of the block. Normal force must also be calculated (mg = n). Data as follows:
Mass of Block : 0.219 kg
Static Friction
|
Total Mass |
Normal Force |
Trial 1 |
Trial 2 |
Trial 3 |
Avg Peak Static Friction |
|
0.219 kg |
2.15 |
1.8 |
2.1 |
1.6 |
1.83 |
|
0.469 kg |
4.60 |
2.7 |
2.8 |
2.3 |
2.6 |
|
0.719 kg |
7.05 |
4.0 |
3.4 |
4.2 |
4.03 |
|
0.969 kg |
9.50 |
4.18 |
5.0 |
5.18 |
4.8 |
|
1.219 kg |
11.95 |
4.6 |
6.5 |
6.5 |
5.9 |
Kinetic Friction
|
Total Mass |
Normal Force |
Trial 1 |
Trial 2 |
Trial 3 |
Avg Kinetic Friction |
|
0.219 kg |
2.15 |
0.77 |
0.65 |
0.6 |
0.67 |
|
0.469 kg |
4.60 |
1.3 |
1.13 |
1.12 |
1.18 |
|
0.719 kg |
7.05 |
1.8 |
1.7 |
1.8 |
1.8 |
|
0.960 kg |
9.50 |
2.25 |
2.6 |
2.4 |
2.42 |
|
1.219 kg |
11.95 |
3.13 |
3.4 |
3.3 |
3.3 |
Questions
When comparing the force required for movement against friction, it is easy to see that force peaks during static friction. Less force is required during kinetic friction.
By looking at the graphs, an lower coefficient of friction is expected for kinetic friction.
10) The coefficient of kinetic friction does not depend on speed because no matter how fast the block was pulled it only affected the levels of static friction
11) The force of kinetic friction would not be affected because it is already in motion. Inertia affects an object’s acceleration therefore, static friction would only be affected.