Name: ______Date: ______Period: _____
Chapter 12.3 Notes
1. Newton’s Third Law of Motion
a. When one object exerts a ______on a second object, the second object exerts an ______and ______force on the first object.
b. The two forces are called ______and ______forces. They are equal in ______and opposite in ______.
2. Action and Reaction Forces
a. ______and reaction forces always come in ______. Whenever there is an ______there must be an ______and opposite ______.
Ex. 1) Two bumper cars colliding
A. Action Force: ______
______
B. Reaction Force: ______
______
Ex. 2) Pressing your hand against the wall
A. Action Force: ______
______
B. Reaction Force: ______
______
Ex. 3) Driving a nail into wood
A. Action Force: ______
______
B. Reaction Force: ______
______
3. Action-Reaction Forces and Motion
a. Some action-reaction forces will cause motion.
Ex. 4) Swimming
A. Action Force: ______
______
B. Reaction Force: ______
______
4. Can action-reaction forces cancel to a net force of zero?
a. ______! The action and reaction ______do not act on the ______object. In example 4, the ______force acted on the ______and the ______force acted on the ______.
b. B. Only when ______act on the ______object can the net force be equal to zero.
5. Momentum
a. Momentum is the ______of an object’s ______and its ______.
b. An object has a ______momentum if the product of its______and velocity is ______. However, when an object is at ______its momentum is equal to ______.
Ex. 5) A large boulder and a small marble
A. If a large boulder and a small marble are slowly rolling toward you which would be easier to stop?
1. ______!!!
2. The marble is ______to stop because it has a much ______mass.
B. Now assume the marble is rolling one ______times faster than the ______. Which would be harder to stop?
1. It ______… Which object has a larger ______of its mass and ______. The larger the ______the larger the ______. The larger the momentum the ______it is to stop the object.
c. The formula for momentum
6. ______; where ______is measured in ______and ______is measured in ______. This means the unit for momentum is ______.
Ex. 6) Which has more momentum? A 0.046 kg golf ball with a velocity of 60.0 m/s or a 7.0 kg bowling ball with a velocity of 6.0 m/s.
Ex. 7) Which has more momentum? A 75 kg runner moving at 2.5 m/s or a 95 kg runner moving at 2.0 m/s?
Ex. 8) Which has a larger velocity? A 2,000 kg car with a momentum of 50,000 kg-m/s or a 16,000 kg semi with a momentum of 30,000kg-m/s.
Ex. 10) A class studied the speed and momentum of a 0.25 kg ball dropped from a bridge. The graph shows the momentum of the ball from the time it was dropped until the time it hit the river flowing below the bridge.
1. At what time did the ball have zero momentum? ______
2. At what time did the ball have the greatest momentum? ______
3. What is the ball’s speed after 1.25 seconds? ______
6. The Law of Conservation of Momentum
a. States that in a ______system, the momentum does not ______nor ______.
b. In a closed system, if no______acts on a system, then the total ______of the system does not ______.
c. In a closed system, the loss of ______of one object equals the ______in momentum of another object. Therefore the momentum is ______.
1. A ______system means other objects and ______cannot enter or leave a ______.
Ex. 11) Train Wrecks
Before Collision After Collision