# Coefficient of kinetic friction lab

• FS98
In summary, the author attempted to find the coefficient of kinetic friction by measuring the acceleration of a mass on a hanger connected to two other masses. The author found that the force on the mass connected to the hanger by the pulley was T - uM1g and the force on the other mass was M2g - T. The author believes that the a would come from the fact that F = ma.
FS98

## Homework Statement

I need to find the coefficient of kinetic friction from a set a lab data that I found. I had a mass connected to a mass hanger by a pulley, and measured the acceleration of the mass with various amounts of mass on the hanger. In the attached image, the acceleration was measured multiple time as M2 was varied and everything else was kept constant.

F = ma

Ff = uFn

## The Attempt at a Solution

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I believe the force on M1 should be T - uM1g and the force on M2 should be M2g - T.

I'm not sure where to go from here. I would be able to solve for u given a single value of a and M2, but I'm not sure how I could solve using the entire set of data. Could I maybe use the average values for M2 and a because the relationship in linear? Or do I have to make a graph of some sort and use the slope to find the value for u from the entire set of data?

#### Attachments

• Untitled-2.jpg
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FS98 said:
'm not sure where to go from here
You measure the acceleration a but your relationship only has a T. What is the link from T to a ?

FS98
BvU said:
You measure the acceleration a but your relationship only has a T. What is the link from T to a ?
I believe the a would come from the fact that F = ma. Replace F with M1a on one side and with M2a on the other. I think we can also get rid of T by substitution.

FS98 said:
I would be able to solve for u given a single value of a and M2, but I'm not sure how I could solve using the entire set of data.
You could find a value for μ from each test, then take the average. Or better, if you plot the calculated μ against M2 you might not get a horizontal line. Some kind of systematic error could result in a sloping or curving line. Then you would try to figure out what the source of error was likely to be and could make an adjustment.

FS98

## 1. What is a coefficient of kinetic friction?

A coefficient of kinetic friction is a value that represents the amount of resistance between two surfaces when one is in motion. It is a dimensionless quantity and is typically denoted by the symbol "μ". It is used to calculate the force of friction between two objects.

## 2. How is the coefficient of kinetic friction measured?

The coefficient of kinetic friction is measured by conducting a friction experiment, commonly known as the "Coefficient of Kinetic Friction Lab". This involves placing two surfaces together and pulling one across the other at a constant speed. The force required to maintain this speed is measured and used to calculate the coefficient of kinetic friction.

## 3. What factors affect the coefficient of kinetic friction?

The coefficient of kinetic friction can be affected by several factors, including the roughness of the surfaces in contact, the weight of the objects, and the type of material the surfaces are made of. Additionally, the presence of lubricants or other substances between the surfaces can also affect the coefficient of kinetic friction.

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

The coefficient of kinetic friction is an important value in engineering and physics, as it is used to calculate the amount of force required to move objects across surfaces. This can be applied in various industries, such as transportation and manufacturing, to optimize the design and efficiency of machines and equipment.

## 5. Can the coefficient of kinetic friction be greater than 1?

No, the coefficient of kinetic friction cannot be greater than 1. This value represents the ratio of the force of friction to the normal force between two surfaces, and it is physically impossible for the force of friction to be greater than the normal force. A coefficient of kinetic friction greater than 1 would indicate that it takes more force to maintain motion than the weight of the object itself, which is not possible.

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