Physics Help: Calculating μ sub s and μ sub k

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In summary, the conversation is about a person who has registered for a forum and is excited to learn about physics. They ask for help calculating μ sub s and μ sub k, and it is mentioned that these coefficients are usually determined through experiments. An example is given of a clock on a horizontal floor and the person asks about the correct value for μ sub s.
  • #1
ItsNoah
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Hi all, I just registered for this forum and I am excited to learn a lot! I am taking physics this year and I am enjoying it a lot although it is quite difficult for me.
Quick question:
how do I calculate μ sub s and μ sub k(formulas would be excellent)?
Thanks!
 
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  • #2
If you're talking about the coefficients of friction for objects, they are typically determined by experiment.
 
  • #3
Pengwuino said:
If you're talking about the coefficients of friction for objects, they are typically determined by experiment.

For example: A 95 kg clock initially a trest on a horizontal floor requires a 650N horizontal force to set it in motion. After the clock is in motion, a horitzontal force of 560N keeps it moving with a constant speed. Find μ sub k and μ sub s between the clock and the floor.

I said the μ sub s was < 650N and > 0 N would that be correct since static friction means it's not moving and if it's between 0 and 650 it will be staying at rest?
 

1. What are μ sub s and μ sub k?

μ sub s and μ sub k, also known as the coefficients of static and kinetic friction, are values that represent the amount of friction between two surfaces. μ sub s is the coefficient of static friction, which measures the amount of force required to start an object moving on a surface. μ sub k is the coefficient of kinetic friction, which measures the amount of force required to keep an object moving at a constant speed on a surface.

2. How are μ sub s and μ sub k calculated?

μ sub s and μ sub k are calculated using the equation: μ = F/N, where μ is the coefficient of friction, F is the force needed to move an object, and N is the normal force (the force exerted by a surface on an object perpendicular to the surface).

3. What factors can affect the values of μ sub s and μ sub k?

The values of μ sub s and μ sub k can be affected by several factors, including the type of surfaces in contact, the roughness of the surfaces, the weight of the object, and the presence of any lubricants or materials between the surfaces.

4. How do μ sub s and μ sub k relate to each other?

The coefficient of kinetic friction, μ sub k, is generally lower than the coefficient of static friction, μ sub s. This means that once an object is in motion, less force is needed to keep it moving than to start it moving. The ratio between μ sub k and μ sub s is known as the coefficient of friction ratio and can vary depending on the surfaces in contact.

5. Why is it important to calculate μ sub s and μ sub k?

Calculating μ sub s and μ sub k is important in understanding the behavior of objects on different surfaces and predicting how much force is needed to move an object. This information is useful in various fields, such as engineering, physics, and everyday life, to ensure the safety and efficiency of objects and systems.

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