STATICS

 Displacement

• The shortest distance between two places and there must be a direction.

According to Newton's first low of motion, any object is rest or moving at constant velocity, if there is no resultant force on that object.

• A force exerted on the body has two effects;  

1. External effect - (change of motion, resisting force)
2. Internal effect - (tendency of the body to deform causes developing stain, stresses.

• Equilibrium of force

1. Vector sum of the all external forces acting on the body must be zero.
2. The sum of external torques must be zero about any point.

Moment

Moment = Fd

SI units - Nm

Couple Moment

• A couple should consist of two parallel forces that are equal in magnitude and opposite in direction.
• must not share same line of action.
• It does not produce any translation, only rotation.
• Moment of the couple about any point is always a constant.
  
  
  

Center of Gravity

• The center of gravity of a body is the single point at which the entire weight of the body can be considered to act.

Stress

• Force per unit area

1. Tensile stress (when  forces pull an object and cause its elongation )
2. Compressive stress ( when forces causes a compression of an object)
3. Bulk stress or Volume stress ( when an object is being squeezed from all aides )
4.  Shear stress ( when deforming forces act tangentially to the object's surface)
5. Torsional stress ( when  force tends to bend and twist a body )