Third Law of Motion - Action and Reaction

Newton's Third Law of Motion states that for every action force, there is an equal and opposite reaction force. These forces act on different objects.

Mathematical Expression

FAB=−FBAF_{AB} = -F_{BA}

where:

  • FAB is the force exerted by object A on object B
  • FBA is the force exerted by object B on object A
  • The negative sign indicates opposite directions

Key Concepts

  • Forces always occur in pairs
  • Action and reaction forces are equal in magnitude
  • These forces act on different objects
  • The forces are simultaneous

Examples in Nature

  • Rocket propulsion
  • Walking
  • Swimming
  • Recoil of a gun