1. ACTION -> REACTION
•Action causes Reaction
• They can be simultaneous,
• but must distinguish cause vs effect
•Action = Distortion, Reaction = Force
• Distortion is due to relative motion between affected
affected parts
• Force causes acceleration and affects further
distortion
• Example:- Pile driving analysis
•Principle of Equivalence:- Gravity = Acceleration
Due to deflection Due to
acceleration/gravity