statics 108

Limiting Friction is that force that must be over come for 2 bodies to move relative to one another.

This force is caused by the nature of the 2 bodies in contact, and by the component of weight acting upon uppermost body

Coefficient of friction is a factor that relates the applied force on an object (such as Weight) to its Friction force, that retards the movement of an object past each other.

Where all the forces in a circumstance all act through one point and they being non parallel their lines of action are concurrent