nota physics vol 4 l six b ( static - equilibrium rigid body and friction )

STATICS

EQUILIBRIUM OF A PARTICLE

Particle A moves to right when F1 > F2

Closed Polygon Of Forces

Triangle of Forces

First Case

METHOD OF VECTOR ADDITION

METHOD OF RESOLVING FORCES

Second Case

METHOD OF VECTOR ADDITION

METHOD OF RESOLVING FORCES

Third Case

EQUILIBRIUM OF A RIGID BODY

Moment of force or torque ( ) = r x F

Magnitude = r F sin θ

Where, r is the position vector for point of action of force from theAxis of rotation and F is the force

Point of action of force

Moment of forces Fr

10 Nm 10 NmAnticlockwise direction (-ve)Clockwise direction ( +ve)

Torque = F x AB

Or ,Torque = F x BA

Action Of Coplanar Forces on A Rigid Body

Case one

FRICTIONAL FORCES• Understand that the action of frictional forces maintains a body in equilibrium.•Understand that the frictional force is a force which has a maximum value of μR

Graph shows a linear relationship between Fs against R

• EQUILIBRUM OF PARTICLE.• EQUILIBRIUM OF RIGID BODIES.• FRICTION FORCE

EXAMPLES

MOMENT AND TORQUE

Pivot

O

FRICTION FORCE