Momentum Conservation (Explosion)

Law of conservation of momentum: in an isolated system (no external force), total linear momentum is constant.

Derived from Newton's 3rd law: internal forces come in equal-and-opposite pairs, so they cancel in total.

In collisions: p_total before = p_total after, ALWAYS (whether elastic or not).

Components: P_x, P_y, P_z all conserved independently — pick axes wisely.

Useful for collisions, explosions, recoil problems (gun-bullet), rocket motion.

Conservation holds in any inertial reference frame; numerical values of P depend on frame, but conservation is universal.

Distinction from energy: momentum is ALWAYS conserved in collisions; kinetic energy is conserved only in ELASTIC collisions.

Photons carry momentum; conservation applies to atomic/nuclear reactions too.