Tire Friction Lab

Background: Static and kinetic friction are a result of two surfaces in contact with each other. Static friction is the friction that must be overcome to start an object moving and kinetic friction occurs in response to two objects in motion relative to one another. The static frictional force is equal to FF (static) = μS FN, where μS is the coefficient of static friction and FN is the normal force. For this lab, you would like your normal force to be equal to the weight of the object. The kinetic frictional force is equal to FF (kinetic) = μK FN.

Driving Question: How does the coefficient of static friction differ between a bald tire and a new tire? Which tire would you prefer and why?

You will be answering this driving question by finding the coefficient of static friction between two different kinds of surfaces: a sandpaper surface and a wood surface. When you write your conclusion, you are going to relate the rougher surface with the higher coefficient of friction to new tires, while relating balding tires to the surface with the lower coefficient of friction.

Introduction: Diagram your setup below indicating all of the necessary values/variables you would be collecting and what equations you will be using.

Procedure: Please write below exactly how you will be carrying out this experiment to find mu, including how you will graph your data to find your coefficient of friction.


Data and Results: All tables, graphs (2) and calculations are to be shown below. Also, clearly label and draw a free body diagram of the system, showing how all forces interact with each other in this experiment.



Conclusion: See the attached writing guide as you will be creating a letter to a friend as your final conclusion. Use the space below for an outline.

Driving Question: How does the coefficient of static friction differ between a bald tire and a new tire? Which tire would you prefer and why?

Assignment:


After completing the lab and determining the coefficient of static friction for a rough and smooth surface, write a conclusion to a friend.


Audience and Purpose:


You are writing to one of your friends who just bought a used car that needs new tires. However, your friend is contemplating buying a new stereo system instead of replacing the currently balding tires. Explain to them using evidence from your lab with actual values why it is important to have new tires as opposed to bald tires.


Length and Form:


3 paragraph letter


Content and Text Structure Requirements:

Intro- State your claim - “I think it is important that you spend your money on new tires rather than bald tires because newer tires have a much higher coefficient of static friction”. This claim also defines what the coefficient of static friction is and what it has to do with tires. You should also give background information on friction in general. Think about any information about friction that is crucial for this experiment!


Body - Present evidence to support the claim using actual data from the lab that new tires stick to the ground better than bald tires. Tell your friend about the experiment performed and then talk about your data. Referencing the graph must be done to help your claim, so you need to do this. Also talk about how consistent your data is.


Conclusion- Create closure by returning to the overall claim and supporting data. Wrap-up strong by giving some facts and/or statistics related to balding tires using data found online.