1. Notes: Friction
Static friction (Fs) is the force that opposes initial motion between two contacting surfaces.
(standing friction)
When a force is applied to an object (Fapplied) and the force of static friction (Fs) opposes it equally, the object does not move.
It is in equilibrium.
-Fapp Fs
NO MOTION

2. Static friction (Fs)
The greatest value of an applied force (Fapplied), before an object starts moving, is Fs,max.
When is Fs,max overcome, the object will move in the direction of the applied force Fapplied.
-Fapp Fs

3. The value of kinetic friction is less than static friction Fk < Fs
Kinetic friction (Fk) is the force that reduces motion between two moving objects, in contact.
(sliding friction)
The value of kinetic friction is less than static friction
Fk < Fs
The total force (Fnet) acting on an object is the difference between the applied force (Fapplied) and the force of kinetic friction (Fk).
-Fk
Fapplied
Fnet = Fapplied - Fk

4. Coefficients of friction m Kinetic = mk = Fk = kinetic friction
Calculating Friction
Friction is directly related to the normal force and the type of surface an object is in contact with
Coefficients of friction m
Kinetic = mk = Fk = kinetic friction
FN normal force
Static = ms = Fs,max = static friction max
FN normal force
Frictional force Ff = m FN
= coefficient of friction x normal force