1. Learning Objectives

2. Principle of Conservation of Momentum In the absence of an external force, the total momentum of a system remains unchanged. If no external force acts on a system, the total momentum before collision (or explosion) is equal to the total momentum after collision (or explosion) or Total momentum = Total momentum before collision after collision

3. Types of CollisionCase 1 : Elastic Collision The colliding objects move separately after collision.

4. u1 v1 v2 u2 m1 m2 m1 m2 Before collision After collision Momentum : m1u1 + m2u2 = m1v1 + m2v2

5. Types of CollisionCase 2: Inelastic Collision The colliding objects move together after collision.

6. u1 v u2= 0 m1 m2 m1 + m2 Before collision After collision Momentum : m1u1 + m2u2 = (m1 + m2)v

7. Types of CollisionCase 3: Explosion The objects involved are in contact with each other before explosion and are separated after the explosion.

8. Before explosion (m1 + m2), u = 0 (m1 + m2)u = m1 v1 - m2v2 v1 v2 m2 m1 After explosion

9. Example 1 Car A Car B Car A of mass 100 kg travelling at 30 m s-1 collides with Car B of mass 90 kg travelling at 20 m s-1 in front of it. Car A and B move separately after collision. If Car A is still moving at 25 m s-1 after collision, determine the velocity of Car B after collision.

10. Example 2 Car A Car B Car A of mass 100 kg travelling at 30 m s-1 collides with Car B of mass 90 kg travelling at 20 m s-1 in front of it. Car A is pulled by Car B with a velocity of 25 m s-1 after collision. Determine the common velocity of Car A and B after collision.

11. Example 3 A bullet of mass 2 g is shot from a gun of mass 1 kg with a velocity of 150 m s-1 . Calculate the velocity of the recoil of the gun after firing.

12. What have you learn today?

13. Homework!! Smile  Teks Book, page 75, no 1-10. Submit: Next week before class. Read subtopic THE CONSERVATION OF MOMENTUM this weekend