彈性碰撞,非彈性碰撞,爆炸既物理力學題點做?

You have to understand the concept behind each phenomenon, not the formula for specific situations.

The most important concepts in collision are:
1. law of conservation of momentum(動量守衡)
2. law of conservation of kinetic energy(動能守衡)

In ealstic collision(彈性碰撞), both momentum and kinetic energy (KE) are conserved.

In an inelastic collision(非彈性碰撞), only momentum is conserved, but not KE.

In an explosion, there is energy input into the system, thus KE is not conserved, but momentum must alwats be conserved.

There are various situations in collision, you have to apply the appropriate laws under each situation. There is no use just blindly to remember equations.