Conservation of momentum in a collision between particles can be understood from

Options

A. conservation of energy
B. Newton's first law only
C. Newton's second law only
D. both Newton's second and third law

Answer

C

Explanation

( c) We know that for a system `F_("ext")=(dp)/(dt)`( form Newton's second law)
If `F_("ext")=0 dp=0 implies p="constant"`
Hence, momentum of a system will remain conserve if external force on the system is zero.
In case of collision's between paritcle equal and opposite forces will act on individual particles by Newton third law, Hence total force on the system will be zero.
Note we should not confuse with system and individual particles. As total force on the system of both particles is zero but force acts on individual particules.