Newton's 3rd law(Laws of Motion)

Newton's 3rd law(Laws of Motion)

We have seen above that Newton's first law of motion defines force. The second law establishes a relation between the external force on a body and its acceleration. The third law tells us the origin of external force on the body that causes acceleration.

Third law- Statement: "To every action, there is always an equal and opposite reaction."

Here, the term action means the force exerted by one body on the other body, while the term re- action means the force exerted by the second body on the first one. If \( \overrightarrow F _{AB} \) is the force exerted on body A by body B (i.e., action) and \( \overrightarrow F _{BA} \) is the force exerted on body B by body A (i.e, reaction) then according to third law \( \overrightarrow F _{AB} \) =-\( \overrightarrow F _{BA} \)
From the above the third law can be stated as follows

Forces always occur in pairs. Force excrted on body by another body is equal and opposite to the force excrted on second body by first one.
Note : Newton's third law is applicable whether the bodies are at rest or in motion.
Note : The third law applies to all types of forces e.g gravitational, electric or magnetic forces etc.