Chapter 6: Momentum and Collisions

1
Chapter 6 Momentum and Collisions

• Section 2 Conservation of Momentum

2
Objectives

• Describe the interaction between two objects in
  terms of the change in momentum of each object.
• Compare the total momentum of two objects before
  and after they interact.
• State the law of conservation of momentum.
• Predict the final velocities of objects after
  collisions, given the initial velocities.

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Momentum is Conserved

• Two soccer balls, pool balls, etc. interact by
  colliding.
• How do the force exerted on ball A and the time
  interval over which it is exerted compare with
  the force exerted on ball B and its corresponding
  time interval?

• The forces are equal in magnitude and opposite in
  direction (Newtons 3rd Law), and the time
  intervals are also equal.

4
Momentum is Conserved

• Two soccer balls, pool balls, etc. interact by
  colliding.
• Using your answer to the previous question,
  determine the change in momentum of each ball.

• The change in momentum of each ball must be equal
  in magnitude but opposite in direction because
  .

5
Momentum is Conserved

• The Law of Conservation of Momentum states the
  following
• The total momentum of all objects interacting
  with one another remains constant regardless of
  the nature of the forces between the objects.

6
Momentum is Conserved

• Momentum is conserved in collisions.
• Momentum is conserved for objects pushing away
  from each other.
• Consumer Focus P. 217

7
Momentum is Conserved

• Sample Problem 6D, P. 218
• Classroom Practice 1-4

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Momentum is Conserved

• Newtons 3rd Law leads to the conservation of
  momentum
• After a collision, the momentum of one object
  increases in direct proportion to the decrease of
  the other object.
• Forces in real collisions are not constant.

9
Assignment

• In Class
• Section Review P. 221 1-4
• Homework
• Problem 6D 1-7