# Coefficient of friction problem

• Sheneron
In summary, the conversation discusses solving for the coefficient of friction for a 4.00 kg block sliding down a 30° incline. The frictional force acting on the block is found to be 9.64 N, and the formula F(friction)=mu*F(normal) is used to find the normal force. To find the normal force, the weight of the block is multiplied by the cosine of 30°. The conversation also emphasizes the importance of drawing a free body diagram to better understand the components of the force.
Sheneron

## Homework Statement

A 4.00 kg block starts from rest at the top of a 30° incline and slides a distance of 2.10 m down the incline in 1.30 s.

## The Attempt at a Solution

I solved for the frictional force acting on the block and got 9.64 N.

I need to solve for the coefficient of friction. I am having some trouble figuring that out. I am not sure how to find the normal force and once i get the normal force do I use the formula force(friction) = mu * normal force

Any help would be appreciated.

F(friction)=mu*F(normal), where F(normal) is the force perpendicular to the surface of the plane that the block is sliding on. It comes from the weight of the block itself. Draw a free body diagram of the block to find the normal force, you'll have to use a bit of trig to get it. Good luck :)

If i multiply the mass by gravity to find the force of it as if it were not on an incline, and then multiply that by the sin of 30, does that give me the normal force?

no it would be cos 30

So it would be 9.8*4 = 39.2, but then do you divide that by cos 30, or multiply it?

if you draw a diagram of the components of the force you will be able to answer this type of question much more easily. You multiply by cos 30

Ok i see that, thank you for your help

## 1. What is the coefficient of friction?

The coefficient of friction is a dimensionless value that represents the amount of resistance between two surfaces in contact with each other. It is typically denoted by the symbol μ and is a measure of the force required to move one surface over the other.

## 2. How is the coefficient of friction determined?

The coefficient of friction is determined by conducting experiments in which a known force is applied to one surface while measuring the resulting frictional force. This process is repeated multiple times, and the coefficient of friction is calculated by dividing the average frictional force by the applied force.

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

The coefficient of friction can be affected by several factors, including the nature of the two surfaces in contact, the roughness of the surfaces, the amount of force applied, and the presence of any lubricants or contaminants.

## 4. What are the different types of coefficients of friction?

There are two main types of coefficients of friction: static and kinetic. The static coefficient of friction represents the amount of force required to initiate movement between two surfaces, while the kinetic coefficient of friction represents the amount of force required to maintain constant movement between two surfaces.

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

The coefficient of friction is a crucial factor in many real-world applications, such as designing machinery, selecting appropriate materials for construction, and predicting the performance of vehicles. It is also used in forensic investigations to analyze the cause of accidents or determine the authenticity of documents.

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