Question

During collision momentum remains constant is it true

Answer 1

It's a false..But after collision it remains constant ...It can states by the law of conservation of linear momentum..

Answer 2

During collision momentum of a body remains constant ?
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No this is statements is not true ,
this will be only and only constant in the case of total momentum as;

》[P1 + P2] = [P3+ P4]
》[ Mv1 + mv2] = [ Mv2 + Mv1]

Hence it is proved