Elastic and Inelastic Collisions

Conservation of Momentum If a system is isolated (no external forces) and a collision occurs, momentum is _______________ Collisions may involve direct contact or actions at a distance (e.g., electric fields) Fig. 6.6, p. 166

Conservation of Momentum Fig. 6.7, p. 167

Collisions Three types of collisions: Elastic: both p and KE are ___________ Inelastic: p is ____________, KE is __________________ Perfectly Inelastic: the objects _________ __________ after the collision so their final velocities are the same. p is conserved, KE is not conserved

Perfectly Inelastic Collisions (1-D) Take care of directions with the ______ for velocities In general we’ll know 4 of the 5 quantities and need to calculate the fifth Also will find the Kinetic Energy lost (KE)

Inelastic Collisions (1-D) Take care of directions with the sign for velocities In general we’ll know 5 of the 6 quantities and need to calculate the sixth Also will find the Kinetic Energy lost (KE)

Elastic Collisions (1-D) We have 2 equations pi = pf (conservation of momentum) KEi = KEf (conservation of energy) Take care of directions with the sign for velocities In general we’ll know 4 of the 6 quantities and need to calculate the other 2

Glancing Collisions (2-D) Fig. 6.15, p. 176 Conservation of Momentum in ____ dimensions Conservation of Energy only if elastic collision

Conservation of Momentum (2-D) x-components: y-components: