Friction and the Road


Diagrams of Road Friction


Our Equipment


Experimental Procedure


Data and Results


What This Means


Tire Sledding!








w = Angular Velocity

Fn = Normal Force

V = Velocity

r = Radius

F = Static Coefficient of Friction

This diagram shows the forces acting on a rotating wheel. These are the primary actual forces acting upon a tire when it is being used. The reason that we did not set up our device as shown above was that it would be rather difficult to measure the frictional force alone and that we wanted to measure the static friction and not the dynamic frictional force because its simplicity of interpretation made our experiment easier to apply. In our experiment, however, we just wanted to measure the amount of friction that different types of tires had, so we ignored all forces upon the tire except the normal force (mg downward) and the frictional static force. Thus our experiment was setup as a box with weight in it and a rope attached at the center of mass which was then attached to a spring scale that measured force in pounds.