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.
