Friction

Friction:
Friction: is contact resistance between two surfaces one of them moves or tends to move relative to the other.









O ? A Friction force balance the applied load “ P“
At “A” Friction Force = Fmax = Fm

Ff =Fmax= ?s N
Further increase of “P“?Sliding of the body
So friction force drops from “Fm” to “Fk ” : Kinetic friction force.

Fm ? N
? Fm= ?s N
?s : Coefficient of static friction
Fk ? N
? Fk= ?k N
?k : Coefficient of kinetic friction















Angles of Friction:


?s : Angle of static friction


?k : Angle of kinetic friction



Problems :
1- To determine the state of the body ( at rest or will slid ). Ff Fm (= ?s N )
2- The motion is known to be impending (i.e. F = Fm=?s N) to determine ?s=?
3- The motion is known to be impending (i.e. F = Fm = ?s N ) to determine the applied load (or one of them ( magnitude or direction)).
Friction:
Friction: is contact resistance between two surfaces one of them moves or tends to move relative to the other.









O ? A Friction force balance the applied load “ P“
At “A” Friction Force = Fmax = Fm

Ff =Fmax= ?s N
Further increase of “P“?Sliding of the body
So friction force drops from “Fm” to “Fk ” : Kinetic friction force.

Fm ? N
? Fm= ?s N
?s : Coefficient of static friction
Fk ? N
? Fk= ?k N
?k : Coefficient of kinetic friction















Angles of Friction:


?s : Angle of static friction


?k : Angle of kinetic friction



Problems :
1- To determine the state of the body ( at rest or will slid ). Ff Fm (= ?s N )
2- The motion is known to be impending (i.e. F = Fm=?s N) to determine ?s=?
3- The motion is known to be impending (i.e. F = Fm = ?s N ) to determine the applied load (or one of them ( magnitude or direction)).