1. Conservation of Momentum Chapter 6 section 2

2. Momentum is Conserved With in a closed system, momentum is conserved. With in a closed system, momentum is conserved. The momentum gained by an object must come from an another object losing momentum. The momentum gained by an object must come from an another object losing momentum. Billiards can be used to Billiards can be used to describe the concept. describe the concept.

3. Law of Conservation of Momentum Law of Conservation of Momentum – The total momentum of all objects interacting with one another remains constant regardless of the nature of the forces between the objects. Law of Conservation of Momentum – The total momentum of all objects interacting with one another remains constant regardless of the nature of the forces between the objects. In other words, the total momentum before a collision is equal to the total momentum after a collision. In other words, the total momentum before a collision is equal to the total momentum after a collision.

4. Conservation of Momentum Equation m 1 v 1i + m 2 v 2i = m 1 v 1f + m 2 v 2f m 1 v 1i + m 2 v 2i = m 1 v 1f + m 2 v 2f Total initial momentum = Total final Momentum

5. Example Problem A 76 kg boater, initially at rest in a stationary 45 kg boat, steps out of the boat and onto the dock. If the boater moves out of the boat with a velocity of 2.5m/s to the right, what is the final velocity of the boat? A 76 kg boater, initially at rest in a stationary 45 kg boat, steps out of the boat and onto the dock. If the boater moves out of the boat with a velocity of 2.5m/s to the right, what is the final velocity of the boat?

6. Example Problem Answer m 1 v 1i + m 2 v 2i = m 1 v 1f + m 2 v 2f Since boat and boater are initial at rest the total momentum before is equal to zero. 0 = m 1 v 1f + m 2 v 2f 0 = (76kg)(2.5m/s)+(45kg)( v 2f ) V 2f = -4.2m/s V 2f = 4.2m/s to the left