Teacher Notes for Momentum and Collisions

 

 

Unit Overview

We estimate this to be an 11-day unit. An additional day should be added for an exam. There are two primary goals for this time:
 

1. To understand the concepts of a momentum change and an impulse and to relate these two quantities to one another in order to predict a numerical value of force, time, mass, or velocity change and to predict the impact that a change in a collision parameter will have upon the collision force.
2. To use momentum conservation to analyze a collision or an explosion occurring in an isolated system to predict an unknown collision parameter or the effect of a change in mass or speed upon the outcome of the collision or explosion.

 

Physics Interactives

We love our simulation section and it has become quite popular in the past decade. The blending of a simulation with a Student Activity sheet and a Concept Checker opens the door for some engaging lesson plans. We have suggested the use of three simulations with the corresponding Student Activity sheet and Concept Checker. Our original vision for how this triad of tools would be used goes something like this:
 

 

Labs

We have proposed four labs for this unit. Since we do not have any Teacher's Guides available, we will supply some notes here:

Lab 1: The first lab requires very little in the way of high-cost equipment. Some inexpensive measuring tape, some large note cards, and some stale marshmallows are all that you need. Students roll the note card into a tube with a diameter the approximate width of a marshmallow. Folding the tube lengthwise and widthwise produces two different sized tubes. They then load the marshmallow at varying locations in each tube and blow with all their might. It is important to keep the same person doing the blowing and blowing in the same way each time. And it is important that the tube is held horizontally on each trial.

Lab 2: Lab 2 might best be done as a demonstration lab. We have provided a Teachers Guide on our Lab page.

Lab 3: Lab 3 requires the use of two carts with spring-loaded plungers. Students "pull the trigger" on the plunger to provide an impulse between carts. They observe or measure the post-explosion speed of the carts. Motion detectors work best for determining the speed. The mass of the carts can be determine using a mass scale. With mass and post-explosion speed of the two carts, students should be able to calculate momentum and show that total system momentum is conserved.

Lab 4: Lab 4 uses ticker tape and ticker tape timers, a cart, and a brick. We find it useful to wrap the brick with strong paper and duct tape to keep it from scratching hands and table surfaces. The brick is held at rest in the cart's path and slightly higher than the cart and released whent the moving cart is underneath. A hit and stick collision occurs and the ticker tapes can be used to determine the speed immediately before and after the collision. We have done similar labs a number of different ways and have found that this level of student seems to understand this method the best. Depending on the ticker tape timer frequency, X dots is equivalent to 1.0 second. Students can manage the math very easily and comprehend that the distance for the X dots provides a measure of speed. To insure best results, call lab groups up one at a time and run their trial, mark the collision point on the ticker tape, hand them the tape, and have them conduct the analysis. This will take 1-2 minutes per lab group. Combining this lab with a Concept Builder is a great way to optimize class time. Lab groups can be working on their Concept Builder before they receive their tape and after they have conducted their analysis.

 

The Calculator Pad

We have provided two CalcPad assignments. Each includes three highly scaffolded problems. The problems step students through the logic of determining a post-collision or a post-explosion speed of an object. The scaffolding will insure the highest likelihood of success and drive home the concept of momentum conservation by the system.

For teachers who wish to provide some problems with less scaffolding or even no scaffolding, you will find plenty of them in the Momentum and Collisions chapter of our Calculator Pad. With a Task Tracker account, you can easily add problems to the sets we have provided for the Conceptual Physics course. You will find directions and video walk-throughs in the Teacher Resources section of your account. With the Task Tracker account, you can even add a third or fourth problem set if you would like. There's no shortage of problems around The Physics Classroom.



 

Science Reasoning Center

We have several Momentum and Collisions activities at our Science Reasoning Center. These provide a slightly different approach than Concept Builders or Minds On Physics. They tend to emphasize less conceptual development and more scientific processing, data interpretation, experimental analysis, etc. They often make great follow-ups to labs and can sometimes be used as an introduction to a topic. For most topics, they are great accompaniments to an NGSS curriculum.

We have included Marshmallow Launcher in our Lesson Plans. It makes a great follow-up to the corresponding lab activity; see Lab 1. For those teachers drawn to this approach, you will find several other Science Reasoning Center activities that fit well with this unit. Consider the following additions:

• Engineering Safer Helmets
• Air Bag Safety
• Collisions

If you have a Task Tracker subscription, visit the Teacher Resources section in order to quickly preview the activity and navigate through all the questions. You will also find information there about NGSS alignments.




 

Other Resources

There are a few resources that we did not list in our Lesson Plans and Learning Outcomes and Activities that you may find to be very helpful. These include:
 

1. Physics Interactives: Egg Drop
   This simulated egg drop activity allows a learner to explore the variables that result in a safe landing or a fractured or broken egg. The accompanying activity sheet emphasizes the use of science reasoning skills to understand the physics behind an egg drop activity.
2. Physics Interactives: The Cart and the Brick
   Our fourth lab is titled The Cart and The Brick. We have a virtual version of this that works quite well. If you don't have ticker tape or ticker tape timers but would like to provide students with the experience, try our simulation. A Student Activity Sheet is available.
3. Physics Interactives: Explosion Analysis
   Our Colliding Carts simulation does explosions as well. Try it with our Student Activity Sheet.
4. Minds On Physics: Mission MC1 on Momentum
   Students recognize the definition, the units, and the vector nature of momentum; and identify the mathematical quantities which effect the momentum and calculate momentum from mass and velocity.
5. Concept Builder: Keeping Track of Momentum - Hit and Bounce
   Students conduct a momentum analysis of a hit-and-bounce collision and to relate the results to the concept of momentum conservation.

 

Teacher Presentation Pack

Here we go again ... throwing in an advertisement in the middle of a Teacher Notes page. But while we are advertising a for-sale item, we are also promoting an item that will potentially save the buyer a load of time. It's our Teacher Presentation Pack. It's a well-worth-the-cost tool for any Physics teacher. But for the early-career and cross-over Physics teacher, it's a life saver ... or at least a time saver. It includes a large collection of Slide Decks, Lesson Notes, animations, and graphics for use in your classroom. Once downloaded, you can modify and customize the Slide Decks as needed. The slides are highly organized and (mostly) graphical; they make great graphic organizers for any student, and especially for the struggling student. Learn more.





 

Also Available ...

Physics teachers may find the following for-sale tools to be useful supplements to our Lesson Plan and Pacing Guide section:

 

1. Task Tracker Subscription (annual purchase)
   A subscription allows teachers to set up classes, add students, customize online assignments, view student progress/scores, and export student scores. Task Tracker accounts allow your students to begin assignments in class or at school and to finish them at home. View our Seat and Cost Calculator for pricing details.
    
2. The Solutions Guide
   We publish a free curriculum with >200 ready-to-use Think Sheets for developing physics concepts. The Solutions Guide is a download containing the source documents, PDFs of source documents, and answers/solutions in MS Word and PDF format. An expanded license agreement is included with the purchase. (Cost: $25 download)
    
3. Teacher Presentation Pack
   This is a large collection of downloadable content packed with nearly 190 Microsoft PowerPoint slide decks, the corresponding Lesson Notes (as PDF and fully-modifiable MS Word format), about 170 animations (in .gif, .png, and .mp4 file formats), a countless number of ready-to-use images (including the original source documents that would allow for easy modification of those images), and a license that allows teachers to modify and use all the content with their classes on password-protected sites (such as course management systems).  (Cost: $40 download)
    
4. Question Bank
   We distribute a Question Bank that includes more than 9300 questions neatly organized according to topic. The Question Bank is the perfect tool for busy teachers or new teachers. Even if you don't use the website with your classes, the Question Bank will assist you in quickly putting together quizzes, tests and other documents with high-quality questions that target student's conceptions of physics principles. And if you do use The Physics Classroom website, the Question Bank is the perfect complement to the materials found at the website. (Cost: $25 download)