Key:
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.
DIAGRAMS
