Section+5.3+-+Elastic+and+Inelastic+Collisions



**__5.3 Review: Elastic & Inelastic Collisions__**  __Elastic Collision:__ a collision in which **kinetic energy is conserved** (i.e. the total kinetic energy after the collision is equal to the total kinetic energy prior to the collision)

//Example: two kinetic balls colliding is an example of an elastic collision as the kinetic energy and the momentum is conserved throughout the system, and the magnitude of the balls’ velocity after the collision are the same magnitude, but in the opposite directions.//  []

**F****ormula for Conservation of Kinetic Energy**

**½ mv12 + ½ mv22 = ½ mv’12 + ½ mv’22**  __Completely Inelastic Collision:__ a collision in which there is usually a maximum decrease in kinetic energy after the collision since the objects collide, become one combined mass and continue to move at one velocity. As such, **energy is NOT conserved during an inelastic collision (partial and complete)**.

//Example: when two cars collide and they stick together, or become one object, then move with the same velocity as one object in the same direction a completely inelastic collision is occurring. Since the cars are stuck indefinitely, they will have the same final velocity and the mass will be the addition of the mass of both vehicles//

 If no momentum is lost, you must prove it using the conservation of momentum equation, but this is only when the net force of the collision is zero.

**mv1+ mv2 = mv’1+mv’2**