Friction between two surfaces

In summary, the lab attempted to prove that the coefficient of friction (Co) would be the same no matter the weight of the mass static on an incline, however their results showed that the Co did change. They were asked if they needed to process the data to find the Co relation, to which they responded that they only needed to find if the Co was independant of mass.
  • #1
jamesyboy1990
16
0

Homework Statement



hi, i am almost done my lab on the coefficient of friction on an inclined plane. I was attempting to prove that the coefficent of static friction would be the same no matter the weight of the mass that was static on the incline. However, i plotted a coefficient versus mass graph, and the line wasn't horizontal (the coefficient changed). My quick question was whether i still need to find the equation for finding the coefficient based on my results, or if i could just conclude that in my case, the coefficient didn't stay constant, and then move to my conclusion

Homework Equations





The Attempt at a Solution

 
Physics news on Phys.org
  • #2
How did you calculate the coefficient of friction for your results?
 
  • #3
i had an incline, measured the weight of the mass, and changed the angle such that if i increased the angle by a little bit, the mass would slide. I did this for several different masses and recorded the angle. I then used a freebody diagram and the equation for static friciton (u = Fmax/R)
 
  • #4
And how did you calculate the normal reaction force?
 
  • #5
R = mg cosx
F = mg sinx

so in essence, the coefficient was tanx
 
  • #6
technically, all i need to know is whether i would have to process the graph to find a relation between weight and the coefficient (although i know that technicallly the coefficient is independant of mass) if all i wanted to prove in the lab was that the coefficient was independant of mass (and in my case, my experimental data didn't prove it)
 
  • #7
Your not actually plotting [itex]\mu[/itex] vs. [itex]m[/itex] what your actually plotting is [itex]\tan\theta[/itex] vs. m since;

[tex]\mu = \frac{F}{R} = \frac{mg\sin\theta}{mg\cos\theta} = \tan\theta[/tex]
 
Last edited:
  • #8
but since tanx = u, so why should it matter whether you plot u vs. m or tanx vs m?
 
  • #9
jamesyboy1990 said:
but since tanx = u, so why should it matter whether you plot u vs. m or tanx vs m?
Indeed, [itex]\tan\theta = \mu[/itex], but are you keeping the angle constant?
 
  • #10
no, because the greater mass wouldn't stay static at the certain angle, so it would decrease.

if i am trying to prove that the coefficient should stay the same, and it doesn't in my experiment, do i have to do more, or can i just stop once the graph shows that the coefficient changed?
 
  • #11
i thought that: Frict max=mu R
so for your experiments to prove mu is irrespective of mass the particle has to be on the point of slipping
that may be too simple i am only doing as physics and you guys might be talking about something higher tho from mechanics mu is >= to R/Frict max
(sorry about symbols ect)
 
  • #12
honestly, the only question i wanted answered was in respect to the set up to the lab. Once you process enough data to prove/disprove the purpose of the lab, do you have to do any more processing, or can you just go straight to conclusion/evaluation?
 

1. What causes friction between two surfaces?

Friction between two surfaces is caused by the microscopic roughness of their surfaces coming into contact with each other. This creates resistance to motion, resulting in the force we feel as friction.

2. How is friction affected by the type of surface?

The type of surface can greatly affect the amount of friction between two surfaces. Smooth surfaces have less friction compared to rough surfaces, as there is less contact between the two. Additionally, different materials can also have varying levels of friction.

3. What factors affect the strength of friction?

The strength of friction is influenced by several factors, including the amount of force applied, the type and roughness of the surfaces, and the presence of lubricants. Friction also increases with the weight of the object and the surface area in contact.

4. How does friction impact motion?

Friction acts in the opposite direction of motion, making it more difficult for objects to move. It can also cause objects in motion to slow down or stop. However, friction can also be beneficial, such as providing traction to prevent slipping.

5. How can friction be reduced or increased?

Friction can be reduced by using lubricants, such as oil or grease, to create a slippery layer between two surfaces. It can also be decreased by using smoother surfaces. On the other hand, friction can be increased by applying more force or using rougher surfaces.

Similar threads

  • Introductory Physics Homework Help
Replies
5
Views
317
Replies
24
Views
1K
  • Introductory Physics Homework Help
Replies
16
Views
3K
  • Introductory Physics Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
7
Views
373
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
9K
Back
Top