Physics lab; deriving for μs and μk

In summary, the conversation is about designing and reporting an experiment to calculate the coefficients of static and kinetic friction between a flat bottomed object and a flat surface. The person is having trouble deriving the expression for μs and μk and has measured the angle at which the object starts to slide. They then show their attempt at a solution, but are unsure if it is correct.
  • #1
Tuccimane
1
0
1. Physics Lab :
Homework Statement

design, run and report an experiment to calculate A) μs B) μk between a flat bottomed object and a flat surface ( include a section called "theory" in which you formally derive an expression for μs and μk )

im basically just having troubles deriving , i measured the angle in which my object has started to slide and its about 10 degrees

2. relevant equations


The Attempt at a Solution


μs :

Fun x = Sum x
0 N = Fg x + Ffs
0 N = mgcos(theta) -μsFN
0 N = mgcos(theta) - μs(mgsin(theta))
mgcos(theta)= μs(mgsin(theta))
mgcos(theta) / mgsin(theta) = μs
μs= cot(theta)

im pretty sure I am supposed to get μs= tan theta, any clue what i did wrong S:
 
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  • #2
Fgx is the sin theta component and FN the cosine component of Fg if theta is the angle that the flat surface makes with the floor.
 

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FAQ: Physics lab; deriving for μs and μk

What is the difference between μs and μk?

μs and μk are both coefficients of friction, but they represent different types of friction. μs is the coefficient of static friction, which is the force needed to overcome the initial resistance of an object at rest. μk is the coefficient of kinetic friction, which is the force needed to keep an object in motion at a constant speed.

How do you calculate μs and μk in a physics lab?

To calculate μs and μk, you will need to perform an experiment using a block of material on a flat surface. You will need to measure the force needed to overcome the initial resistance of the block (for μs) and the force needed to keep the block in motion at a constant speed (for μk). Then, you can divide the force by the normal force (the force perpendicular to the surface) to calculate the coefficients of friction.

What factors can affect the values of μs and μk?

The coefficients of friction can be affected by several factors, including the type of material of the block and the surface it is on, the weight of the block, and the amount of force applied. Additionally, temperature and humidity can also impact the values of μs and μk.

Why is it important to determine the coefficients of friction in a physics lab?

Determining the coefficients of friction is important because it helps us understand the behavior of objects on different surfaces. It can also help engineers design and build structures and machines that are more efficient and have less wear and tear due to friction.

How can the coefficients of friction be used in real-world applications?

The coefficients of friction are used in many real-world applications, such as designing tires for cars, determining the stopping distance of a vehicle, and calculating the force needed to move heavy objects. They are also used in the development of sports equipment, like the grip of a tennis racket or the speed of a skateboard.

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