$K.E=\frac{1}{2}mv^2$ , $P=mv$ thus there is a relation between them. I really cantcan't understand why there is no decrease in momentum when kinetic energy is decreased in an inelastic collision. I am only a high school passed student(ready for college). Should iI leave this question until iI learn "Lagrangian" and "Noether's Theorem" ? Because iI literally read most of the answers about these kindkinds of questions and spend almost half a day foron it, BUT iI do not get it. Can anyone please answer this question.? please help me..