Exploring Different Collision Types

Types of Collisions and Conservation of Momentum

Ever wonder what happens when two cars crash or billiard balls collide? In physics, we classify collisions into three main types. In a perfectly inelastic collision, objects stick together after colliding, moving as one mass. The equation $M_1V_1 + M_2V_2 = M_{12}V$ helps us calculate their final velocity.

In a regular inelastic collision, objects deform during impact and lose kinetic energy, but continue moving separately afterward. Despite this energy loss, momentum remains conserved, following $M_1V_1 + m_2V_2 = m_1v_1 + m_2v_2$.

A perfectly elastic collision occurs when objects bounce off each other with no energy loss—like a ball bouncing back to its original height. All other real-world collisions fall somewhere in between, being partially elastic. For explosions, which are like collisions in reverse, we use $m_{Total}V = m_1V_1 + m_2V_2$.

Remember This! The principle of conservation of momentum works because of Newton's Third Law—during a collision, the impulse (and therefore momentum change) experienced by one object equals the opposite impulse experienced by the other.

Let's see this in action with examples: When an 8,000 kg train car moving at 10 m/s collides with a stationary 2,000 kg car and they stick together, their final velocity is 8 m/s. For two colliding billiard balls in an elastic collision, we can calculate that if one rebounds at 0.4 m/s, the other must move at -0.606 m/s to satisfy conservation of momentum.