Friction Lab

Experiment 1

Pre-Lab notes
Key questions?
IV: Fn  
DV:  Ff
CV:  Surface

How is the friction force affected when the surfaces are pressed together harder?
Prediction: The friction force increases where there is more weight and the surfaces are pressed together harder

How does the material of the surface affect the friction?
Prediction: Some materials are bumpier which causes more friction and when they aren't as bumpy there is less friction because things aren't getting caught on each other

Apparatus: Dual-range Force Sensor, block with different material on each surface, lab quest mini, and weights

Procedure:
Trial 1:
1) Get materials
2) use logger pro
3)test the felt side of the block with no weight by pulling it on a flat surface at a constant speed.test by doing what exactly?  If this is all I saw I would have no idea what to do....
4) test with added weight  and take what data?  from where?  can you see that if this is all I saw then I would not know what to do?

Trail 2:
1)test the rubber side of the block with no weight
2) Add weight

Data set 1 (weight of block 65g)
felt side
Fn(N)                     Ff(N)
0.637N                 0.17N
1.127N                0.285N
1.617N                0.375N
2.597N                0.533N
5.537N                1.444N

VM: As more mass is added the normal force increases, this makes the force of friction increase
MM: Ff=(0.260n/n)Fn - 0.03N
Slope: For every 1N of the Fn, the friction increases by 0.260N
Y-int: When the normal force is 0, the force of friction is -0.03


Data set 2
rubber side
Fn(N)                  Ff(N)
0.0637N             0.789N
1.127N               1.269N
1.617N               1.734N
2.597N               2.531N
5.537N               6.136N


VM: As the masses increase the normal force increases, this also makes the force of friction increase
MM: Ff = (1.09n/n)Fn - 0.02N
Slope: For every  1N from Fn, the friction increases by 1.09N
Y-int: When the normal force is 0N, the force of friction -0.02N is....
Mu - coefficient of friction
Ff=(1.3n/n)Fn
Ff= MuFn

                            Affects Ff

• materials
• how hard surfaces press together 

Experiment #2
Velocity
IV: velocity
DV: Ff
CV: Fn (mass) surfaces

Purpose Question
How does the velocity  affect the Ff?
I will change the velocity of the block by pulling it at different speeds. Then I will measure the Ff and see the relation.

Procedure
We will change the speeds of the block to measure if that is what affects the force of friction. We will keep the surfaces we use the same and pull the block at a constant speed.

Trial 1
  V          Ff
Slow     .74N
Med      .80N
Fast       .84N

No relationship and no effect
b/n Ff velocity

Experiment 3
surface area

Procedure
Get the block of wood that you can change the surface area. Pull the block of wood at a constant speed. Then test the force of friction.
IV: surface area
DV: Ff
CV: Speed , surface materials

The surface area does not affect the force of friction.

We are trying to find out what affects the force of friction? Is it the weight added to a surface, velocity, or the surface area? To figure out if it was the surface we tested for the force of friction we kept everything the same but changed the type of surface. To figure out if it was the velocity we kept everything the same except the speed she pulled the block at. To find out if it was the surface area we kept everything the same but changed the side she pulled the block on.

The slopes of the equations are different because it depends on the friction of every surface. The y intercepts are also similar because they are close to zero because they are not moving at the y intercept. The slope of the equation is telling us the force of friction between the surfaces when there is weight added on the surfaces. The equation for the calculation for force of friction is Ff= MuFn not 1.3...  the generic mu in the main equation...  this paragraph somewhat confusing.,.,..that's it for the rewrite??  I said the paragraph was confusing....??

In experiments 2 and 3 the graphs tell me that the the force of friction was not affected. In these experiments we tested if the velocity and surface area would affect the force of friction but they did not because the graphs tell us the force of friction stays the same the whole time.

It is possible for 2 different people wearing the same shoes to have different forces of friction. If the people weight differently that will affect the friction because that means that persons shoes press harder on the floor so those surfaces will get caught on each other even more. yesIt is also possible for two people wearing different shoes to have the same force of friction because it depends on the amount of weight added to the surfaces and the material of the shoes could be the same.more specifically what.,.,.?

One error could be that we weren't always pulling the block at a constant speed. Another error could be that the surfaces were not always the same the whole experiment like if one part of the table had more friction than the other.

Gravity Lab

Data Analysis: labels and units!

0.06kg            0.589

0.07kg            0.681 

0.08kg            0.786 

0.09kg            0.891 

0.1kg              0.997

VM: As the weight  mass increases, the force increases.

MM: Fg = (10.26N/Kg)mass-0.0032N

Slope: For every 1 Kg added, the force increases by 10.26 N.

Y-int: Where the mass is zero Kg, the force is -0.0032N

(the y-int should be 0 because if there is nothing hanging there would be no force)

Claims/Evidence/Conclusion

Mass and weight are both different. Mass is the measure of matter in an object while weight is the measure of how hard gravity is pulling an object. Everyones graph is the same becasue the amount strength of the field of gravity on an object is ALWAYAS the same and they are all linear.. Our graph is a bit different from others because we had different masses but everyone has similar slopes. Fg=mg means that the force is equal to mass x gravity. It gives you the amount of pull on the mass due to gravity.all points are there....  but conclusion could be better written, clearer, and proofread it!

Dueling Buggy Lab

- Objective:  The objective was to figure out the point that the two buggies would meet going in opposite directions. 

- Your Plan- : We laid out 3 meter sticks and marked every 2 feet with a piece of tape. We took a video of each buggy and with that we found the exact time it took for them to travel every 2 feet and a time it took to travel a total of 10 feet. 

-Data Analysis:  After we collected the data for both cars we then calculated the speed measured in feet per seconds for each. HOW did you get these speeds? Once we got the speed we created a y=mx+b equation. M= their speed, b= their starting position, x= their time, and y= their position. good!For the fast buggy we got y=1.37x and the slow buggy was y=-.5x+10. We graphed these equations using a calculator and found the point of intersection: 7.33 feet and 5.35 seconds. We tested it out and it was right. where is the graph?

-Using your Model/Designing a Solution:  When asked where they would intersect starting at 4 feet, we plugged 4 in for 10 in the equation for the slow buggy because that would be the new starting point. After graphing with a calculator we concluded that the intersection would be at 3 feet in around  2.13 seconds. Once we tested it out our predictions were correct. 

Buggy Lab

Pre-Lab observations

-Stays in a straight line
-moves
-noise
-has head lights and antenna
-wheels
-red
-forward only
-keeps going
-two seats

 

Objective
What is the relationship between it's position and time?

The Plan
For both our trials we will start the buggy at zero and time how long it takes for it to move 20 inches constantly.add a bit more - how will you time it?  who will do what job?

Data Analysis 

-Trial 1 

why so many decimal places?

-Trial 2

Data Graph

VM - As the position increases, the time increases proportionally
MM -  Position = (20.8 in/sec) time + -20.8in
Slope - For every second, the position increases 20 inches
Y-int - The the amount of seconds equal zero the position is -20.8 inches

 

VM - As the time increases, the position increases consistently 

MM - Position = (19.7 in/sec) time+ -9.5 in

Slope - For every second,  the position increases 10 inches  why 10?  isn't it 19.7?  or 20 if you round?

Y-int- The amount of seconds equal zero the position is -9.5 inches    

Conclusion
In each of the experiments the buggy was moving in either a positive  direction position or a negative position, this made the slope positive or negative. All of the buggy's move at a constant speed so all the experiments have a linear trend. Since all of the buggy's speeds are similar, all graphs have a similar slope. Even though they have similar slopes they each have a different starting position so each graph has a different y-intercept.nice!
In our experiment we had a few errors. Our reaction time for the timer was not completely accurate. Also our marks for when to stop the timer differed slightly each time. A better way to have gotten our data would be to take a video of the buggy moving next to the meter sticks and to pause the video to time the Buggy at a more accurate mark.great idea!!

Journal Statement 

I liked this experiment because it was a good one to start the year off with so that we could get used to how to do these lab blogs. good!

Earth-Moon Lab

I could not figure out the scale of the distance between the moon and the earth. I figured out that the earths diameter is equal to about three moons. We also figured out the real diameter of the moon and the earth. With the information we had, we tried dividing the numbers but we did not get the correct answers.
That's ok you were close - you just needed to next scale the real distance to the paper earth.  :)