1. Momentum and Its Conservation
Chapter 9
Momentum and Its Conservation

2. 9.1 Impulse and Momentum
Newton called momentum “the quantity of motion.”
- He wrote his three laws in terms of momentum.
How is velocity affected by force?
- Newton’s second law

3. Relating impulse to momentum
F = ma = m ∆v/∆t
F∆ t = m ∆v
Using the impulse – momentum theorem
F∆ t = p2 – p1
where p2 = mv2
and p1 = mv1

4. 9.2 Conservation of Momentum
Two particle collision
Because the time intervals are the same for the collision of the two particles, the momenta must be the same
momenta before = momenta after

5. Momentum in a closed system
A system that does not gain or lose mass is said to be a closed system. Also, all forces affecting the system are internal forces. The net external force on a closed system is zero and the system is called an isolated system.

6. Conservation of Momentum law
The momentum of any closed isolated system with no external force does not change.

7. Explosions
Just like a collision only backwards.
Two-dimensional collisions
The law of conservation of momentum holds true regardless of the directions of the objects before and after collision.
Remember, momentum p, is a vector and all the vector rules apply.