1. Physical Science Chapter 12 Section 3
Newton’s Third Law
Physical Science
Chapter 12
Section 3

2. Action & Reaction Forces
When objects collide there are two forces
The force being exerted on the second object and…
The force being exerted by the second object onto the first object that is equal in size but opposite in direction

3. Conservation of Momentum
Total momentum after collision = Total momentum before collision

4. Conservation of Momentum
How is rocket propulsion an example of the conservation of momentum?

5. Momentum
How does moving the glove back change the force?

6. Momentum The product of mass and velocity of an object Equation:
P = m x v
P = momentum (kg x m/s and direction)
M = mass (kg)
V = velocity (m/s)

7. Momentum
Calculate the momentum of a 6 kg bowling ball moving at 10 m/s down the alley toward the pins.
P = m x V
Mass, m = 6 kg
Velocity, v = 10 m/s
Momentum, p = ? Kg x m/s (and direction)
P = (6 kg) x (10 m/s) = 60 kg x m/s

8. Review
A 75 kg speed skater has a speed of 16 m/s moving forward. What is the momentum?

9. Review
A 135 kg ostrich is running north at 16.2 m/s. What is the momentum?

10. Review
A 5 kg baby is on a train moving east at m/s. What is the momentum?

11. Review
A 48 kg passenger is seated on a train that is stopped. What is the momentum?

12. Review
Calculate the velocity of a 0.8 kg kitten with a forward momentum of 5 kg x m/s.

13. Review
A runner, who has a mass of 52 kg, has a momentum of 218 kg•m/s along a trail. What is the runner’s velocity?

14. Review
What is Newton’s third law of motion?

15. Review
How is momentum calculated?

16. Review
Explain what the law of conservation of momentum means.

17. Review
Which of the following models explains why the action and reaction forces don’t cancel each other when a soccer ball is kicked?
The force of the player’s foot on the ball is greater than the force of the ball on the player’s foot.
The forces do not act on the same object
The reaction force happens after the action force

18. Review
How does mass affect momentum?