How do I find the coefficient of friction?

In summary, the conversation discusses a physics experiment and the steps taken to determine the average negative acceleration, rolling friction force, and coefficient of rolling friction. The final solutions are found to be -0.1324 m/s^2, 218.4223N, and 0.014, respectively. The concept of normal force and its relation to gravitational force is also mentioned.
  • #1
SpecialOps0
21
0

Homework Statement


Please help this is due tomorrow. I was made to do an experiment and here it is.

I had to designate a fixed starting point, drive at 10 mph until that point, put the car into neutral and see how far it drifted until it stopped. Then I was instructed to go the opposite way and do the same thing.

Average rolling distance: 55.125 meters
Weight of the car: 1649.7154 kg, or 1617.2109 Newtons
Radius of tires: .333 meters
Time Taken average: 34 seconds

I'm suppose to find the average negative acceleration of my car, the rolling friction during the experiment and the coefficient of rolling friction.

Homework Equations


N/A, show if you used different..


The Attempt at a Solution



My attempt is below I'm not sure how to get much more than the average negative acceleration.

10 mph = 4.5 m/s (for convenience)

Average neg accel: (0-4.5m/s)/34 seconds = -.1324 m/s^2

Frictional force: 16167.2109N * .1324 = 2190.5387N

Coefficient of rolling friction: (10^2)/(2*9.8*55.125) = .0926N

Again I'm confused on coeff of rolling friction
 
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  • #2
SpecialOps0 said:

Homework Statement



The Attempt at a Solution



My attempt is below I'm not sure how to get much more than the average negative acceleration.

10 mph = 4.5 m/s (for convenience)

Average neg accel: (0-4.5m/s)/34 seconds = -.1324 m/s^2

Frictional force: 16167.2109N * .1324 = 2190.5387N

Coefficient of rolling friction: (10^2)/(2*9.8*55.125) = .0926N

Again I'm confused on coeff of rolling friction

Force is mass times acceleration, so instead of 16167.2109 N, you should use 1649.7154 kg.

Coefficient of friction is simply the ratio of frictional force and normal force. Normal force is equal to gravitational force (why?)
 
  • #3
So it's 1649.7154 * .1324 = 218.4223N for the force?

and 218.422/16167.2109 = .0135 For the frictional rolling?

My teacher never explained this and I can't find it in my textbook other than in more advanced chapters I don't understand.
 
  • #4
Yes, that looks right.
 
  • #5
Thank you all who helped :D this is now my new favorite site haha.
 
  • #6
Ooops I meant
218.4223N is the rolling force?

.0135 is the coefficient ?
 
  • #7
Yes, as Sourabah N noted, that looks correct. Except you should round off your answers to 2 significant figures. 220 N is the rolling friction force, and 0.014 is the rolling friction coefficient.
 
  • #8
Thanks again sorry I mixed up my labeling before.

Does the .014 have a label as N?
 
  • #9
SpecialOps0 said:
Thanks again sorry I mixed up my labeling before.

Does the .014 have a label as N?

Sourabh N said:
Force is mass times acceleration, so instead of 16167.2109 N, you should use 1649.7154 kg.

Coefficient of friction is simply the ratio of frictional force and normal force. Normal force is equal to gravitational force (why?)
Again as noted above, the coefficient is force unit divided by force unit, so does it have any units?
 
  • #10
No, ok ty :).
 

1. How do I measure the coefficient of friction?

To measure the coefficient of friction, you will need to perform an experiment using an inclined plane or a friction tester. The experiment involves gradually increasing the angle of the plane or the weight on the friction tester until the object begins to move. The angle or weight at which the object starts to move is then used to calculate the coefficient of friction.

2. What factors affect the coefficient of friction?

The coefficient of friction is affected by several factors, including the type of surfaces in contact, the roughness or smoothness of the surfaces, and the amount of force pressing the surfaces together. Other factors that can influence the coefficient of friction include the presence of lubricants or contaminants on the surfaces and the temperature at which the experiment is conducted.

3. How does the coefficient of friction impact motion?

The coefficient of friction determines the amount of resistance a surface has to an object in motion. A higher coefficient of friction means there is more resistance, which can result in slower or more difficult movement. On the other hand, a lower coefficient of friction means less resistance and easier movement.

4. Are there different types of coefficient of friction?

Yes, there are two types of coefficient of friction: static and kinetic. Static friction is the resistance between two surfaces when they are not moving relative to each other, while kinetic friction is the resistance when the surfaces are in motion. The coefficients of static and kinetic friction may differ depending on the surfaces and conditions involved.

5. How can the coefficient of friction be used in real-life applications?

The coefficient of friction has many practical applications, such as determining the amount of force needed to move an object, designing and improving machines and tools, and developing safer and more efficient transportation methods. It is also important in sports and athletics, where athletes strive to minimize the coefficient of friction to increase speed and performance.

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