Applied Mechanics and Graphic Statics
If the given forces P₁, P₂, P₃ and P₄ are such that the force polygon does not close, then the system will

Always reduce to a resultant force
Be in equilibrium
Always reduce to a couple
Both (A) and (C)

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Applied Mechanics and Graphic Statics
The following statement is one of the laws of Dynamic friction

For moderate speeds the force of friction remains constant but decreases slightly with the increase of speed
The magnitude of the kinetic friction bears a constant ratio to the normal reaction between two surfaces. The ratio being slightly less than that in the case of limiting friction
The force of friction always acts in a direction opposite to that in which a body is moving
All of these

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