BdMO Online Forum

Dear Friends,

I want a proof of Newton's third law.Can u give me an easy proof?

Newton's 1st and 3rd law can be derived from the 2nd one.Then why we say Newton's three laws of motions?We should say Newton's law of motion.We should see them as one.

Best Wishes
Rafi

The first and third law cannot be derived from the second law. The first law and third law are postulates; there is no proof or derivation for them, only experimental evidence. The second law is an experimental result.

if u want a good experience of the third law then PUNCH on a wall

In fact the first law postulates the existence of inertial frames in which the other laws are applicable.

then shouldn't we use axioms or postulates instead of law. isn't it confusing.

"Axiom" is mostly used in mathematics. In mathematics laws are proved from axioms. But in physics experimental results are called laws.

Newton's 3rd law may be formally stated:

"Forces always occur in pairs. If object A exerts a force F on object B,
then object B exerts an equal and opposite force –F on object A"

or in slogan style:

"Every action has an equal and opposite reaction"

Who asked for a statement of Newton's third law?