Newton Third Law of motion-Mechanics

To every action, there is always an equal and opposite reaction.

Forces always occur in pairs. Force on a body A by B is equal and opposite to the force on the body B by A.

There is no cause effect relation implied in the third law. The force on A by B and the force on B by A act at the same instant.

Action and reaction forces act on different bodies, not on the same body. Consider a pair of bodies A and B. According to the third law, FAB = – FBA.

(force on A by B) = – (force on B by A)

Thus if we are considering the motion of any one body (A or B), only one of the two forces is relevant. It is an error to add up the two forces and claim that the net force is zero.

However, if you are considering the system of two bodies as a whole, FAB and FBA are internal forces of the system (A + B). They add up to give a null force. Internal forces in a body or a system of particles thus cancel away in pairs. This is an important fact that enables the second law to be applicable to a body or a system of particles.

The great brain behind this laws Sir Isaac Newton .

Related posts :

Newton's First law of motion
Newton's second law of motion
Concept of momentum
Uniform circular motion
Projectile motion





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