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Chapter 9: Lesson 2 - Conservation of Momentum, and Math
Chapter 9: Lesson 2 - Conservation of Momentum, and Math
Quick Vocabulary Lesson
Quick Vocabulary Lesson
Before we talk about conservation of momentum, we need to talk about systems. A system is a defined collection of objects. Our Honors Physics classroom at CHS is room 124. Everything inside room 124 can be thought of as one system, the physics room system.
A closed, isolated system, is where objects cannot enter or leave the system. If our room 124 system was closed and isolated, then no objects including people, could enter or leave the classroom.
An internal force is a force that happens between objects within a system. If we moved all the desks from the front of room 124, to the back of room 124, that does not change our system. All the objects are still in room 124.
An external force is a force that originates from a source other than the objects in the system. If Mrs. Sultana pushed a desk from her room into our room, room 124, then that would change our system. External forces change a system, just like Mrs. Sultana's desk would change our system of our room.
Law of Conservation of Momentum
Law of Conservation of Momentum
The law of conservation of momentum states that the momentum of any closed, isolated, system does not change.
It doesn't matter how many objects are in the system, it is only necessary that no objects enter or leave the system. The momentum changes are equal in magnitude and opposite in direction.
Conservation of Momentum with Collisions
Conservation of Momentum with Collisions
The momentum before the collision will always equal the momentum after the collision.
Elastic Collision
Elastic Collision
In elastic collisions, the momentum before the collision will equal the momentum after the collision. The momentum of the red ball before the collision plus the momentum of the white ball before the collision will equal the momentum of the red ball after the collision plus the momentum of the white ball after the collision
Inelastic Collision
Inelastic Collision
In inelastic collisions, the momentum before the collision will equal the momentum after the collision. The momentum of the blue train before the collision plus the momentum of the red train before the collision will equal the combined mass of both trains times the combined velocity of both trains after the collision.
Equations
Equations
It will be helpful to have your equation sheet ready. A copy of the equation sheet is under resource materials on this website and on google classroom. It can also be found HERE.
Practice the Momentum Math!
Practice the Momentum Math!
Click here for the paper that I use in the video. As you watch this video, pause it and try the math on your own. When you have your answer, start the video and see if you are right. It is important to know where YOU make your mistakes so you can correct them for next time!
Remember there are more practice math problems under Chapter 9 Resources. Practice the math and see if your answer matches my answer.
Practice these Math Problems Before Class!
Practice these Math Problems Before Class!
Click on the picture to take you to the practice problems that I will be going over the next time we have class. Remember, you need to try the problems on your own to see where you make your mistakes if you want to learn how to do the math problems on your own.
You have finished Lesson 2!
You have finished Lesson 2!
Be sure to head over to google classroom and fill out the exit pass.
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