Friction Lab

Friction Lab

Experiment 1

Pre-Lab Notes:
Experiment 1:  How is the friction force affected when the surfaces are pressed together more?
IV: Normal Force
DV: Friction Force
CV: Velocity, Surface Area
Secondary Experiment: Change the surface.
Prediction: If the surface forces are pressed harder together, the friction force will increase.
Apparatus (list): A surface, a block with felt on one side and rubber on the other side, lab quest mini, computer, dual force sensor, masses

Procedure: First we are going to find the weight MASSof the block and convert it into Newtons. Next, we are going to chose one side of the block, the felt or the rubber, and we are going to drag (pull) the sensor with the block attached to it. After this we will take the data from the testing with the sensor. We are then going to add various masses to the block and redo the same experiment but with more mass on the block. We will do this two times for each side of the object (felt and rubber).not super clear how your measurements became Ff and Fn
Data Collection and Analysis
Primary Experiment (felt side):

VM: As the normal force increases, the force of friction increases proportionally.

MM: Ff= (.1813 N/N) x Fn - .011N

Slope: For every 1N added to Fn, the force of friction increases by .1813 Newtons.

Y intercept: When Fn (newtons) is at zero, the force of friction is -.011Newtons.

Secondary Experiment (rough side):

VM: As the normal force increases, the force of friction increases proportionally.

MM: Ff (1.2538 N/N) x Fn - .4991N

Slope: For every 1N added to Fn, the force of friction increases by 1.2538 Newtons.

Y intercept:  When Fn (newtons) is at zero, the force of friction is -.4991 Newtons.

Experiment 2: How does the Velocity affect the force of Friction?
IV: Velocity
DV: Ff
CV: Fn (Mass), Surface materials

Apparatus: A surface, a block with felt on one side and rubber on the other side, lab quest mini, computer, dual force sensor, masses
Procedure: In order to test how the velocity affects the force of friction, i will use the friction block (felt side) and pull at different speeds. Then im going to measure the force of friction using the force probe at each speed. I will be sure to keep the same mass (fn) and surface.

Force of Friction vs. Velocity

Force of Friction is not affected by the velocity.

Experiment 3: How does the surface area affect the force of Friction?
IV: Surface Area
DV: Ff
CV: Speed, Surface materials

Procedure: First we will get a big block of wood where we can change the surface area. After we know how much surface area each side of the block has, we will test the force of friction on each side of the wood by pulling it with the dual force sensor. During this experiment we will drag the piece of wood at a constant speed and we will keep the same surface material.

Data Collection and Analysis

Force of friction is constant

Conclusion         

In the Friction Lab experiments, we had to test how various actions would change or affect the force of friction. To do this we did 3 different experiments. In the first experiment we tested whether the friction force was affected when the surfaces are pressed together. In the second experiment we tested whether the velocity affected the force of friction. And lastly for the third experiment we tested whether the surface area affected the force of friction. Ultimately, we found out that only changing the amount of pressure of an object will affect the the force of friction. Furthermore, changing the velocity and the surface area does not affect the force of friction. So, in the big picture, this lab helped our study of friction because now we recognize applying more pressure is the only way that the force of friction changes.and changing the surface itself

For Experiment one, after doing this lab and graphing the data, I noticed that everyone had very similar graphs with proportionally increasing force of friction as the normal force increases. In comparison to other groups, our normal force and force of friction were slightly different. But they were generally all relatively the same. The reason both graphs have different slopes is because the amount of friction that each side of the block gives up is different, hence one side is felt and one is rubber. The felt side of the block has a smaller slope because it produces the least amount of friction. However, the rubber side has a larger slope because the rubber material causes more friction because it is preventing movement. The slope basically represents the material (felt or rubber) and therefore corresponds to the surface that is on the block as it creates creates friction. The more friction that is created, the larger the slope, the less friction that is created, the smaller the slope will be. To calculate the force of friction you have to use this equation : F(f)=µ(fn). This is called the coefficient of friction.

For Experiment two, we were testing whether the velocity affected the force of friction. After, testing this and graphing this experiment as a class we noticed that the force of friction was not affected by the the velocity. For experiment three, we tested whether the surface area affected the force of friction as class as well. After testing the experiment and graphing it, we found that the force of friction was constant. Therefore, the force of friction was not affected by the surface area. Both of these experiments came out the exact way i predicted. I thought that neither of them would affect the force of friction.

It is possible for two people wearing identical shoes to have different forces of friction because of two big factors, the mass and the surface. These two factors are what cause the force of friction to vary. Therefore, if two people have different masses, then the one with the heavy mass has more force of friction than the person that has a smaller mass. This is due to the normal force. Futhermore, if they are on different surfaces, there forces of friction will be different because some surfaces may be rougher and some may be smoother. 

It is possible for two people wearing different types of shoes to have the same amount of friction. However, the two people must have different masses. They can not have the same mass. The shoe with more friction must be worn by a lighter person and the won with less friction worn by a heavier person.
So in summary, the mass and the type of surface determine how much force of friction an object will feel/have. However, friction does not depend on the amount of surface area in between the moving object or the speed of the object.

One main source of error that I saw was the use of different tables. Some of these tables may have been sticky, bumpy, and or not the same. This error can be fixed by using one single table that is cleaned and that every group uses. This way everyone can get the same or about the same data without these factors messing up our data. Another source of error would be the method of pulling the vinyl side of the block. This is because the vinyl side had more friction causing it to be more jerky and harder to pull. We could have fixed this by just pulling at a constant speed and not trying to pull harder when the friction would slow it down and cause it to jerk around.
I am very interested in friction due to this lab. I want to learn more in depth about it. I want to know how to determine the strength of the friction and the main types of friction.

After completing this lab, i was very happy. I thought this was a very successful lab. I thought everything went well except for our sources of error. Furthermore, I believe I am becoming better at writing labs in physics class. Every lab i do becomes easier and easier to write. Practice makes perfect and I really enjoy these labs. And I hope to write better on each one.

excellent work Tommy!