Momentum and Its Conservation Chapter 9 Momentum and Its Conservation

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

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

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

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.

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

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.