### Introduction

The coefficient of friction is a measurement of the ease with which two materials slide past each other. Different combinations of materials have different coefficients of friction. For instance, the coefficient of friction between a bicycle’s rubber tire and a paved road surface is much greater than the coefficient of friction between a sled and snow. The coefficient of friction is usually given the Greek letter mu (μ) in mathematical relationships.

Scientists have long recognized that the coefficient of friction is different when two objects are moving relative to each other or at rest. Imagine trying to slide a large refrigerator across a kitchen floor. It takes more force to get it moving than to keep it moving—this is because the coefficient of static (not moving) friction is greater than the coefficient of kinetic (sliding) friction.

In this experiment, you will record video of a sliding object and use video analysis tools to determine the coefficient of kinetic friction.

### Objectives

In this experiment, you will

• Measure the motion of a sliding object.
• Evaluate the forces acting on a sliding object.
• Determine the coefficient of kinetic friction between the sliding object and the surface on which it is sliding based on the acceleration of the sliding object.