1. Elastic and Inelastic Collisions

2. 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

3. Conservation of Momentum
Fig. 6.7, p. 167

4. 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

5. 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)

6. 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)

7. 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

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

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