Applied Mechanics and Graphic Statics
The following is not a law of static friction:

The force of friction always acts in a direction opposite to that in which the body tends to move
The force of friction is dependent upon the area of contact
The force of friction depends upon the roughness of the surface
The magnitude of the limiting friction bears a constant ratio to the normal reaction between two surfaces

ANSWER DOWNLOAD EXAMIANS APP

Applied Mechanics and Graphic Statics
The characteristic of a couple is:

All listed here
Algebraic sum of forces, constituting a couple is zero
A couple can be never the balanced by a single force
Algebraic sum of moments of forces, constituting a couple, about any point, is same

ANSWER DOWNLOAD EXAMIANS APP