Friction Co-Efficient

Friction Laboratory

1 Abstract

This report details an experiment to prove that there is a relationship between the normal force applied to a weight and the maximum force friction can apply, it also details an experiment to find a value of this constant for four different metals. This report shows that there is a relationship between the normal force and the maximum force friction can apply and that it is generally constant for a given material.

2 Introduction

This assessment acted as an introduction to friction and the theory of static friction co-efficient. I was tasked with finding the static friction co-efficient for a range of materials via experimental methods and using the formula given above.

The main aim of the experiment was to test a number of materials and find their co-efficients via an experiment using blocks of the chosen material and a weighted system to act as the force.

I tested four materials

- Brass

- Steel

- Aluminium

- Cast iron

3 Theory

Static coefficient of Friction

Between two solids there is a static friction co-efficient ((), which is defined as the ratio between the tangent force (F) required to produce a sliding effect over the normal force between the two surfaces.

(=F/N

This means that on a perfectly horizontal surface the force (F) required to move a solid resting on a flat surface is:

F=( x mass of solid x gravity

As the normal force increases the Force required to move the weight increases by a constant amount due to the co-efficient ( being constant. The force required to start moving an object is equal to the maximum friction force the material can apply. Once the applied force is greater than the maximum friction force the weight will start to move at an accelerating speed.

The friction co-efficient is a constant between the two materials and as such if either the normal is increased (by increasing the mass of the object)...