We thus have: ddt(→p1+→p2)=∑→Fext Furthermore, if we introduce the “total momentum of the system”, →P=→p1+→p2, as...We thus have: ddt(→p1+→p2)=∑→Fext Furthermore, if we introduce the “total momentum of the system”, →P=→p1+→p2, as the sum of the momenta of the individual particles, we find: d→Pdt=∑→Fext which is the equivalent of Newton’s Second Law for a system where, →P, is the total momentum of the system, and the sum of the forces is only over external …