Finding the friction coefficient?

In summary, the conversation discusses determining the minimum coefficient of static friction between the tires and the road in order to accelerate a Porsche at 11.2 m/s2 without spinning the tires. The equation fs/N=coefficient is mentioned, but the person is unsure of how to apply it without knowing the mass or acceleration. The other person suggests using the Newton 2 equation and considering the net force in the x direction, potentially eliminating the need for the mass.
  • #1
papi
31
0

Homework Statement



Hopping into your Porsche, you floor it and accelerate at 11.2 m/s2 without spinning the tires. Determine the minimum coefficient of static friction between the tires and the road needed to make this possible.

Homework Equations




well I know fs/N= the coefficient, however, even though N=ma, you dnt have an m nor an a. i just dnt see adequate info given. help!
 
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  • #2
papi said:

Homework Statement



Hopping into your Porsche, you floor it and accelerate at 11.2 m/s2 without spinning the tires. Determine the minimum coefficient of static friction between the tires and the road needed to make this possible.

Homework Equations




well I know fs/N= the coefficient,
yes
however, even though N=ma,
why do you say N=ma?
you dnt have an m nor an a. i just dnt see adequate info given. help!
the acceleration, a, is given. Write the Newton 2 equation, looking in the x direction. What's the net force in that direction? Maybe you won't need to know m
 
  • #3


I would first like to commend you for recognizing the importance of finding the friction coefficient in this situation. The coefficient of static friction is a crucial factor in determining the maximum acceleration that can be achieved without causing the tires to spin.

In this case, we can use the equation fs = μsN, where fs is the maximum force of static friction, μs is the coefficient of static friction, and N is the normal force between the tires and the road. As you correctly pointed out, N = ma, where m is the mass of the vehicle and a is the acceleration.

Since we are given the acceleration (11.2 m/s2), we can rearrange the equation to solve for N: N = ma/μs. Now, we need to determine the mass of the vehicle. This information is not explicitly given, but we can estimate it based on the fact that it is a Porsche. According to the Porsche website, the average weight of a Porsche 911 is around 3,153 lbs or 1,430 kg.

Plugging in the values, we get N = (1,430 kg)(11.2 m/s2)/μs. Now, we need to determine the maximum force of static friction (fs). This can be calculated using the equation fs = μsN. However, since we are trying to determine the minimum coefficient of static friction, we can assume that the maximum force of static friction is equal to the weight of the vehicle (mg).

Therefore, we can set mg = μsN and solve for μs: μs = mg/N. Plugging in the values, we get μs = (1,430 kg)(9.8 m/s2)/(1,430 kg)(11.2 m/s2) = 0.69.

Therefore, the minimum coefficient of static friction between the tires and the road needed to accelerate at 11.2 m/s2 without spinning the tires is 0.69. However, this is just an estimate and the actual coefficient may vary depending on factors such as road conditions and tire type. It is always important to exercise caution and drive safely, even with a high-performance vehicle like a Porsche.
 

1. What is the friction coefficient?

The friction coefficient is a measure of the amount of resistance between two surfaces in contact with each other. It is a dimensionless number that represents the ratio of the force required to move one surface over the other to the force holding the two surfaces together.

2. How is the friction coefficient determined?

The friction coefficient is typically determined experimentally by measuring the force required to move one surface over the other at a constant speed. This force is then divided by the weight of the object to obtain the friction coefficient.

3. What factors affect the friction coefficient?

The friction coefficient can be affected by a variety of factors, including the type of materials in contact, the roughness of the surfaces, the force holding the surfaces together, and the presence of lubricants or contaminants.

4. How is the friction coefficient used in real-world applications?

The friction coefficient is an important parameter in engineering and design, as it helps determine the amount of force needed to move objects, the amount of wear on surfaces, and the efficiency of various mechanical systems. It is used in everything from designing car brakes to creating non-slip surfaces.

5. Can the friction coefficient be changed?

Yes, the friction coefficient can be changed by altering the factors that affect it, such as using different materials, adding lubricants, or changing the surface roughness. However, it is a fundamental property of the materials and cannot be completely eliminated.

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