When a nucleus at rest spontaneously splits into fragments of mass m1 and m2, the ratio of the momentum of m1 to the momentum of m2 is

  p₁ = - p₂

the moment value of the two particles is the same, but its direction is opposite

Explanation:

When a nucleus divides spontaneously, the moment of the nucleic must be conserved, for this we form a system formed by the initial nucleus and the two fragments of the fission, in this case the forces during the division are internal and the moment is conserved

initial instant. Before fission

               p₀ = 0

since they indicate that the nucleus is at rest

final moment. After fission

              = m₁ v₁ + m₂ v₂

             p₀ = p_{f}

             0 = m₁ v₁ + m₂v₂

             m₁ v₁ = -m₂ v₂

              p₁ = - p₂

this indicates that the moment value of the two particles is the same, but its direction is opposite

scientific laws are the result of testing theories and proving them to be facts.