1. Newton’s 3 rd Law of Motion: Momentum

2. Section 3: The Third Law of Motion Objectives: State Newton’s third law of motion. Identify action and reaction forces. Calculate momentum. Recognize when momentum is conserved.

3. Third Law of Motion The third law states that for every action (force) in nature, there is an equal and opposite reaction. For example, if object A exerts a force on object B, then object B also exerts an equal and opposite force on object A. The forces are exerted on different objects.

4. Newton’s 3rd Law of Motion (cont.) Examples: – Swimming- arms push against water, water pushes swimmer ahead – Rocket Propulsion- hot gases produced by burning fuel are pushed out of the engine’s nozzle, pushing the rocket or car ahead

5. Momentum: Related to the amount of force that is needed to change the motion of a moving object. Which is more difficult to stop… a semi-truck or VW Beetle? *** depends on velocity and mass Increase in mass or velocity results in an increase in momentum. Law of Conservation of Momentum: The total amount of momentum in a system is conserved.

6. Momentum Sports Example Football linemen- hard to start moving, hard to stop moving!

7. Momentum: Equation: Momentum = Mass x Velocity SI Units: kg x m/s (and direction) p = mv

8. Momentum Problem What is the momentum of a 10.0 kg bowling ball moving down a bowling alley at 6.0 m/s? Known: m = 10.0 kg v = 6.0 m/s Unknown: p = ___kg x m/s Formula: p = mv p = 10.0 kg x 6.0 m/s = 60 kg x m/s