Presentation on theme: "Chapter 9 9-2 Momentum and Its Conservation. 9.2 Conservation of Momentum System is a defined collection of obj ects."— Presentation transcript:
Chapter Momentum and Its Conservation
9.2 Conservation of Momentum System is a defined collection of obj ects.
Newtons 3rd Law & Momentum Impulse-Momentum Theorem is another way of stating Newtons 3rd Law. A system is isolated if no net external forces acts on it. The momentum is conserved.momentum
Figure 9-5 p 181 shows momentum.
Law of Conservation and Momentum Momentum of any closed, isolated system does not change. Fig pa + pb = p a + p b mava + mbvb = mava + mbvb
This fig. shows that when cars A & B collide, p is conserved. Example Problem 209 Practice Problems 210
Internal and External Forces Internal forces cannot change total momentum. External forces the system is not closed and momentum is not conserved. Its important to define a system carefully. The total momentum of an isolated system is constant.
Conservation of Momentum in Two Dimensions Total momentum is the vector sum of the momenta of all the parts of the system. Ex Pr Recoil 212 Prac Pr 213
Figure 9-10 p 214 Ex Problem Prac Pr 216
9.2 The Conservation of Momentum Newtons 3rd law is another statement of the law of conservation of momentum. The law of conservation of momentum states: In a closed, isolated system, the total momentum of the system does not change. The momentum of a system changes when it is not isolated, that is, when a net external force acts on it.