# Can conservation of momentum related to Newton's first law?

I know this is a scrap of thought, but the first law states that (from Wikipedia):

If an object experiences no net force, then its velocity is constant

Is it describing the conservation of momentum $p_{before} = p_{after}$? Where $p=mv$, so that in a regime of 'undisturbed motion' (although no such thing may actually exist) the momentum is conserved?

In case the answer to the first question is 'yes', then the second question is, how can I elaborate this idea a bit more?

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On which ground you've put -ve sign to right hand side using Newton's 1st Law? –  Sachin Shekhar Jan 10 at 7:38
Yea, you are right. I used the third-law's logic in the equation. But the question is still similar. Sorry for that. –  SHY.John Jan 10 at 7:55
Newton's first law you mention applies to one body. Yes, the statement $v=const$ means $p=const$ for one particle. However for an isolated ensemble of interacting particles there is a total momentum that conserves too despite each individual momentum is not conserved due to interactions. The latter is derived from the second Newton's law, i.e., from the equations of motion.