Static friction constant and Kinetic friction constant

Thread starter sfsy1
Start date Aug 20, 2010
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Constant Friction Kinetic Kinetic friction Static Static friction

In summary, the static friction constant and kinetic friction constant are two different measures of the force required to overcome and maintain motion between two surfaces. The kinetic friction constant is always lower than the static friction constant and the two are related by μ<sub>k</sub> = μ<sub>s</sub> * N. The factors that affect these constants include the type and roughness of the surfaces, as well as the normal force and materials involved. These constants can be measured experimentally with a friction tester and can change over time due to various factors such as wear and tear, temperature, lubricants, and changes to the surfaces or materials.

Aug 20, 2010

sfsy1

max [tex]\mu[/tex]_s is always larger than [tex]\mu[/tex]_k.

i think it's proven experimentally, but why exactly is this so?

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Aug 21, 2010

torquil

I'd think because at rest a higher strength bond is allowed to form between the two surfaces?

1. What is the difference between static friction constant and kinetic friction constant?

The static friction constant is a measure of the amount of force required to overcome the initial resistance between two surfaces at rest. On the other hand, the kinetic friction constant is a measure of the force required to maintain the motion between two surfaces that are already in motion.

2. How are static friction constant and kinetic friction constant related?

The kinetic friction constant is always lower than the static friction constant because it takes less force to maintain motion than it does to overcome the initial resistance and start motion. The two constants are related by the equation: μ_k = μ_s * N, where μ_k is the kinetic friction constant, μ_s is the static friction constant, and N is the normal force acting between the two surfaces.

3. What factors affect the static friction constant and kinetic friction constant?

The static and kinetic friction constants are affected by the type of surfaces in contact, the roughness of the surfaces, and the amount of force pressing the surfaces together (normal force). The coefficient of friction, which is a measure of the friction constants, also depends on the materials and their properties.

4. How do you measure the static friction constant and kinetic friction constant?

The friction constants can be measured experimentally by using a device called a friction tester. The tester applies a known force to the surface and measures the amount of force required to start or maintain motion. The ratio of these forces gives the friction constants.

5. Can the static and kinetic friction constants change over time?

Yes, the friction constants can change over time due to wear and tear on the surfaces, changes in temperature, or the presence of lubricants. The constants can also change if the surfaces are altered or if the materials are replaced with different ones.